Karl-Jochen Stein - Academia.edu (original) (raw)
Papers by Karl-Jochen Stein
The steadily increasing demand on the natural stone market is accompanied by a predominantly poor... more The steadily increasing demand on the natural stone market is accompanied by a predominantly poor economic balance in the extraction of the raw material "ornamental stone". Thus, the net production of raw blocks is far too low in relation to the resulting overburden, which is often the result of insufficient geoscientific input and evaluation of the deposit itself and the deposit-controlling factors.Under these conditions, the investigation pursued the goal of capturing an essential part of the geological conditions with the analytical observation of the fractures systems, in order to contribute to an optimized stone extraction. Only by critically derived constraints on the quarrying process based on the geological situation can the economic viability of natural stone deposits be maintained or increased in the long term, and this from an environmentally friendly point of view.Profitable dimensional stone production mainly depends on the number of extracted blocks. Compared...
Zusammenfassung Bei dem für die Eugen-Geinitz-Sicht in Usadel ausgewählten Findling (Fundort: ver... more Zusammenfassung Bei dem für die Eugen-Geinitz-Sicht in Usadel ausgewählten Findling (Fundort: vermutlich Kiesgrube Siedenbüssow) handelt es sich um ein seltenes monomiktes Konglomerat, dessen Herkunft – und damit auch sein Bildungsalter – bisher nicht genau bestimmt werden kann. In einer sandigen bis feinkiesigen, rötlich-violetten Matrix befinden sich zahlreiche helle, mäßig gerundete Gesteinsbruchstücke bis 12 cm Größe aus kristallinem Quarz (Gangquarz). Konglomerate mit einer ähnlichen Zusammensetzung sind als lokale Einschaltungen in mesoproterozoischen Sandsteinen und Grauwacken an der Hohen Küste in Nordschweden bekannt und möglicherweise als isolierte Vorkommen im gesamten Verbreitungsgebiet jotnischer Rotsedimente zu finden. Aufgrund der Zusammensetzung und des relativ geringen Verfestigungsgrades kann aber auch eine Zuordnung zur klastischen Abfolge der jüngstproterozoisch-unterkambrischen Nexö-Formation Bornholms nicht völlig ausgeschlossen werden, deren basale Schichten e...
Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, 2013
Engineering Geology, 2017
Several factors determine building stone exploration in order to maximize the extraction, process... more Several factors determine building stone exploration in order to maximize the extraction, processing and application of these natural materials. Some factors are intrinsic to stones, such as their physical-mechanical properties, while others are related to their exploitability, such as quarry reserves or fracturing density. During an exploration campaign, these factors are not always considered or properly weighed in terms of the negative consequences on quarry activities or rock behaviour under particular conditions. In this study, two well-known Portuguese granites are assessed to highlight the main factors. These granites have different characteristics, weathered and sound, and are exploited in quarries with different joint densities. The most relevant physicalmechanical properties were evaluated and related to the specific petrophysical features of each granite. The fracture patterns were identified in the quarries and then modelled in order to compute the quarry yield. The weathered granite shows an important microcrack network and a general alteration of the rock-forming minerals, which has an important impact on its physicalmechanical properties and on the resistance to environmental factors. Moreover, the extreme differences in the degree of weathering require careful choices for the possible applications. In both quarries, the joint sets are similar to the regional faulting, but some random joints can be found and, consequently, diminish the quarry yield. The development of horizontal sheet joints during the exploitation process could have a great influence on the quarry productivity if they are not used do delimitate the extracted blocks. The modelling of the natural fracture pattern allows us to determine the potential volume of blocks that could be exploited. However, the quality of the information gathered could lead to an over-estimation of the quarry production. This example show the importance of the exhaustive researches during a building stone assessment campaign.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
Litos La Revista De La Piedra Natural, 2008
Slates were traditionally used as roofing material or for cladding worldwide and also in Uruguay.... more Slates were traditionally used as roofing material or for cladding worldwide and also in Uruguay. In regions where this resource was easily mined, the widespread application of slates in constructions resulted in the development of characteristic cultural landscapes. The application of slates in a wider sense is nowadays open for all uses of dimensional stone, compared to the restricted use as roofing or cladding material in the past. This has been achieved by the discovery and mining of new deposits within the last 25 years worldwide. Furthermore, the optimization of mining techniques that allows the excavation of larger blocks and the technical development for further handling of the blocks has contributed to an open spectrum of applications. The slate deposits from Uruguay are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano Belt. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are loc...
Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, 2013
Environmental Earth Sciences, 2012
In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There i... more In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There is a long tradition in Uruguay, as well as worldwide, of using dimensional stones in architecture and art, specially granitic ones. Some of the present applications of these dimensional stones are as façade cladding, countertops, and outdoor and indoor floor slabs. The color spectrum of the Uruguayan granitic dimensional stones varies from black to light gray, covering a wide variety of red and pink and minor greenish-gray. The décor of these granitic dimensional stones is mainly determined by their fabric, fundamentally the grain size and the color distribution between the different minerals that compose the rocks. In the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties. A detailed structural analysis has been performed in several deposits, as well as the application of the software 3D Block Expert for modeling the possible raw block size distribution. Other factors controlling the mining viability of the deposits were also studied (e.g., homogeneity/heterogeneity of color and décor) and the possible reserves were calculated.
Environmental Earth Sciences, 2012
Slates are internationally known as roof and façade-cladding material since prehistoric times. Th... more Slates are internationally known as roof and façade-cladding material since prehistoric times. The methods required to mine and manufacture these dimensional stones are relatively simple in comparison to those utilized in granitic dimensional stones. This has led to a worldwide rentable commercialization of slate in the last centuries and also to the development of characteristic cultural landscapes. In Uruguay several slates are mined and used in architecture, especially as façade cladding and floor slabs. The most important slates regarding their production and utilization are the dolomitic slates. These dolomitic slates are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano belt. Representative samples have been geochemically and petrographically characterized, as well as petrophysically and petromechanically analyzed. The petrophysical and petromechanical properties were investigated in a very systematic way with respect to the new European standards, showing values comparable to those registered for internationally known slates. Detailed structural and deposit analysis were carried out in Uruguay in order to evaluate the dolomitic slate deposits. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are located in the limb of a regional fold, where bedding and cleavage are parallel. The main lithotype is a layered and fine-grained dolomitic slate with a quite diverse palette of colors: light and dark green, gray, dark gray, reddish and black. The mined slate is split into slabs 0.5-2 cm thick. In the past, the average production in Uruguay was around 4,000 tons/year and a historical maximum of 13,000 tons was reached in 1993 (Oyhantçabal et al. in Z dt Ges Geowiss 158(3):417-428, 2007). The oscillations in the regional demand were the cause of several flourishing and decay cycles in the activity, but our investigation shows a considerable volume of indicated resources and therefore a very good potential.
Environmental Earth Sciences, 2010
Dimensional stones with a black color occupy a prominent place on the international market. Urugu... more Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic-basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material. Keywords Dolerites Á Black dimensional stones Á Petrophysical properties Á Structural analysis Á Block size distribution Á Uruguay
1. Fundorte und historische Bezüge Anlässlich des Kolloquiums des Geowissenschaftlichen Vereins N... more 1. Fundorte und historische Bezüge Anlässlich des Kolloquiums des Geowissenschaftlichen Vereins Neubrandenburg zum 100. Jahrestag eines Vortrages des Geologen Prof. Eugen Geinitz vor dem Großherzoglichen Haus von Mecklenburg-Strelitz am 5.3.1912 in Neustrelitz zur Landesgeologie von Mecklenburg erwähnte Herr Erwin Hemke in seinem Vortrag einen großen Findling im Revier Waldsee. Der Verfasser nahm dies zum Anlass, die größeren Findlinge im Revier Waldsee zu erfassen und zu beschreiben. Die Findlinge liegen überwiegend abseits der Wege und sind daher kaum bekannt. Der größte Stein („Waldsee-Findling“) liegt etwa 1 km südlich der Goldenbaumer Mühle und 50 m südwestlich eines Waldweges, der die Grenze zwischen Nationalpark und Landesforst bildet, direkt neben einer 2012 umgestürzten Traubeneiche mit über 1 m Durchmesser (ehemaliges Naturdenkmal). Beim Aufsuchen des Steins sollte der direkt auf dem Weg wachsende Bestand des Wald-Bingelkrauts (Mercurialis pernnes), eine botanische Rarität...
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 3... more 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 ... Dimensional stones in Uruguay: situation and perspectives ... Pedro Oyhantçabal, Siegfried Siegesmund, ...
Slates are internationally known as roof and façade-cladding material since prehistoric times. Th... more Slates are internationally known as roof and façade-cladding material since prehistoric times. The methods required to mine and manufacture these dimensional stones are relatively simple in comparison to those utilized in granitic dimensional stones. This has led to a worldwide rentable commercialization of slate in the last centuries and also to the development of characteristic cultural landscapes. In Uruguay several slates are mined and used in architecture, especially as façade cladding and floor slabs. The most important slates regarding their production and utilization are the dolomitic slates. These dolomitic slates are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano belt. Representative samples have been geochemically and petrographically characterized, as well as petrophysically and petromechanically analyzed. The petrophysical and petromechanical properties were investigated in a very systematic way with respect to the new European standards, showing values comparable to those registered for internationally known slates. Detailed structural and deposit analysis were carried out in Uruguay in order to evaluate the dolomitic slate deposits. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are located in the limb of a regional fold, where bedding and cleavage are parallel. The main lithotype is a layered and fine-grained dolomitic slate with a quite diverse palette of colors: light and dark green, gray, dark gray, reddish and black. The mined slate is split into slabs 0.5-2 cm thick. In the past, the average production in Uruguay was around 4,000 tons/year and a historical maximum of 13,000 tons was reached in 1993 (Oyhantçabal et al. in Z dt Ges Geowiss 158(3):417-428, 2007). The oscillations in the regional demand were the cause of several flourishing and decay cycles in the activity, but our investigation shows a considerable volume of indicated resources and therefore a very good potential.
Dimensional stones with a black color occupy a prominent place on the international market. Urugu... more Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic-basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material.
In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There i... more In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There is a long tradition in Uruguay, as well as worldwide, of using dimensional stones in architecture and art, specially granitic ones. Some of the present applications of these dimensional stones are as façade cladding, countertops, and outdoor and indoor floor slabs. The color spectrum of the Uruguayan granitic dimensional stones varies from black to light gray, covering a wide variety of red and pink and minor greenish-gray. The décor of these granitic dimensional stones is mainly determined by their fabric, fundamentally the grain size and the color distribution between the different minerals that compose the rocks. In the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties. A detailed structural analysis has been performed in several deposits, as well as the application of the software 3D Block Expert for modeling the possible raw block size distribution. Other factors controlling the mining viability of the deposits were also studied (e.g., homogeneity/heterogeneity of color and décor) and the possible reserves were calculated.
The steadily increasing demand on the natural stone market is accompanied by a predominantly poor... more The steadily increasing demand on the natural stone market is accompanied by a predominantly poor economic balance in the extraction of the raw material "ornamental stone". Thus, the net production of raw blocks is far too low in relation to the resulting overburden, which is often the result of insufficient geoscientific input and evaluation of the deposit itself and the deposit-controlling factors.Under these conditions, the investigation pursued the goal of capturing an essential part of the geological conditions with the analytical observation of the fractures systems, in order to contribute to an optimized stone extraction. Only by critically derived constraints on the quarrying process based on the geological situation can the economic viability of natural stone deposits be maintained or increased in the long term, and this from an environmentally friendly point of view.Profitable dimensional stone production mainly depends on the number of extracted blocks. Compared...
Zusammenfassung Bei dem für die Eugen-Geinitz-Sicht in Usadel ausgewählten Findling (Fundort: ver... more Zusammenfassung Bei dem für die Eugen-Geinitz-Sicht in Usadel ausgewählten Findling (Fundort: vermutlich Kiesgrube Siedenbüssow) handelt es sich um ein seltenes monomiktes Konglomerat, dessen Herkunft – und damit auch sein Bildungsalter – bisher nicht genau bestimmt werden kann. In einer sandigen bis feinkiesigen, rötlich-violetten Matrix befinden sich zahlreiche helle, mäßig gerundete Gesteinsbruchstücke bis 12 cm Größe aus kristallinem Quarz (Gangquarz). Konglomerate mit einer ähnlichen Zusammensetzung sind als lokale Einschaltungen in mesoproterozoischen Sandsteinen und Grauwacken an der Hohen Küste in Nordschweden bekannt und möglicherweise als isolierte Vorkommen im gesamten Verbreitungsgebiet jotnischer Rotsedimente zu finden. Aufgrund der Zusammensetzung und des relativ geringen Verfestigungsgrades kann aber auch eine Zuordnung zur klastischen Abfolge der jüngstproterozoisch-unterkambrischen Nexö-Formation Bornholms nicht völlig ausgeschlossen werden, deren basale Schichten e...
Jahresberichte und Mitteilungen des Oberrheinischen Geologischen Vereins, 2013
Engineering Geology, 2017
Several factors determine building stone exploration in order to maximize the extraction, process... more Several factors determine building stone exploration in order to maximize the extraction, processing and application of these natural materials. Some factors are intrinsic to stones, such as their physical-mechanical properties, while others are related to their exploitability, such as quarry reserves or fracturing density. During an exploration campaign, these factors are not always considered or properly weighed in terms of the negative consequences on quarry activities or rock behaviour under particular conditions. In this study, two well-known Portuguese granites are assessed to highlight the main factors. These granites have different characteristics, weathered and sound, and are exploited in quarries with different joint densities. The most relevant physicalmechanical properties were evaluated and related to the specific petrophysical features of each granite. The fracture patterns were identified in the quarries and then modelled in order to compute the quarry yield. The weathered granite shows an important microcrack network and a general alteration of the rock-forming minerals, which has an important impact on its physicalmechanical properties and on the resistance to environmental factors. Moreover, the extreme differences in the degree of weathering require careful choices for the possible applications. In both quarries, the joint sets are similar to the regional faulting, but some random joints can be found and, consequently, diminish the quarry yield. The development of horizontal sheet joints during the exploitation process could have a great influence on the quarry productivity if they are not used do delimitate the extracted blocks. The modelling of the natural fracture pattern allows us to determine the potential volume of blocks that could be exploited. However, the quality of the information gathered could lead to an over-estimation of the quarry production. This example show the importance of the exhaustive researches during a building stone assessment campaign.
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
Litos La Revista De La Piedra Natural, 2008
Slates were traditionally used as roofing material or for cladding worldwide and also in Uruguay.... more Slates were traditionally used as roofing material or for cladding worldwide and also in Uruguay. In regions where this resource was easily mined, the widespread application of slates in constructions resulted in the development of characteristic cultural landscapes. The application of slates in a wider sense is nowadays open for all uses of dimensional stone, compared to the restricted use as roofing or cladding material in the past. This has been achieved by the discovery and mining of new deposits within the last 25 years worldwide. Furthermore, the optimization of mining techniques that allows the excavation of larger blocks and the technical development for further handling of the blocks has contributed to an open spectrum of applications. The slate deposits from Uruguay are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano Belt. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are loc...
Schriftenreihe der Deutschen Gesellschaft für Geowissenschaften, 2013
Environmental Earth Sciences, 2012
In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There i... more In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There is a long tradition in Uruguay, as well as worldwide, of using dimensional stones in architecture and art, specially granitic ones. Some of the present applications of these dimensional stones are as façade cladding, countertops, and outdoor and indoor floor slabs. The color spectrum of the Uruguayan granitic dimensional stones varies from black to light gray, covering a wide variety of red and pink and minor greenish-gray. The décor of these granitic dimensional stones is mainly determined by their fabric, fundamentally the grain size and the color distribution between the different minerals that compose the rocks. In the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties. A detailed structural analysis has been performed in several deposits, as well as the application of the software 3D Block Expert for modeling the possible raw block size distribution. Other factors controlling the mining viability of the deposits were also studied (e.g., homogeneity/heterogeneity of color and décor) and the possible reserves were calculated.
Environmental Earth Sciences, 2012
Slates are internationally known as roof and façade-cladding material since prehistoric times. Th... more Slates are internationally known as roof and façade-cladding material since prehistoric times. The methods required to mine and manufacture these dimensional stones are relatively simple in comparison to those utilized in granitic dimensional stones. This has led to a worldwide rentable commercialization of slate in the last centuries and also to the development of characteristic cultural landscapes. In Uruguay several slates are mined and used in architecture, especially as façade cladding and floor slabs. The most important slates regarding their production and utilization are the dolomitic slates. These dolomitic slates are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano belt. Representative samples have been geochemically and petrographically characterized, as well as petrophysically and petromechanically analyzed. The petrophysical and petromechanical properties were investigated in a very systematic way with respect to the new European standards, showing values comparable to those registered for internationally known slates. Detailed structural and deposit analysis were carried out in Uruguay in order to evaluate the dolomitic slate deposits. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are located in the limb of a regional fold, where bedding and cleavage are parallel. The main lithotype is a layered and fine-grained dolomitic slate with a quite diverse palette of colors: light and dark green, gray, dark gray, reddish and black. The mined slate is split into slabs 0.5-2 cm thick. In the past, the average production in Uruguay was around 4,000 tons/year and a historical maximum of 13,000 tons was reached in 1993 (Oyhantçabal et al. in Z dt Ges Geowiss 158(3):417-428, 2007). The oscillations in the regional demand were the cause of several flourishing and decay cycles in the activity, but our investigation shows a considerable volume of indicated resources and therefore a very good potential.
Environmental Earth Sciences, 2010
Dimensional stones with a black color occupy a prominent place on the international market. Urugu... more Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic-basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material. Keywords Dolerites Á Black dimensional stones Á Petrophysical properties Á Structural analysis Á Block size distribution Á Uruguay
1. Fundorte und historische Bezüge Anlässlich des Kolloquiums des Geowissenschaftlichen Vereins N... more 1. Fundorte und historische Bezüge Anlässlich des Kolloquiums des Geowissenschaftlichen Vereins Neubrandenburg zum 100. Jahrestag eines Vortrages des Geologen Prof. Eugen Geinitz vor dem Großherzoglichen Haus von Mecklenburg-Strelitz am 5.3.1912 in Neustrelitz zur Landesgeologie von Mecklenburg erwähnte Herr Erwin Hemke in seinem Vortrag einen großen Findling im Revier Waldsee. Der Verfasser nahm dies zum Anlass, die größeren Findlinge im Revier Waldsee zu erfassen und zu beschreiben. Die Findlinge liegen überwiegend abseits der Wege und sind daher kaum bekannt. Der größte Stein („Waldsee-Findling“) liegt etwa 1 km südlich der Goldenbaumer Mühle und 50 m südwestlich eines Waldweges, der die Grenze zwischen Nationalpark und Landesforst bildet, direkt neben einer 2012 umgestürzten Traubeneiche mit über 1 m Durchmesser (ehemaliges Naturdenkmal). Beim Aufsuchen des Steins sollte der direkt auf dem Weg wachsende Bestand des Wald-Bingelkrauts (Mercurialis pernnes), eine botanische Rarität...
Zeitschrift der Deutschen Gesellschaft für Geowissenschaften, 2007
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 3... more 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 ... Dimensional stones in Uruguay: situation and perspectives ... Pedro Oyhantçabal, Siegfried Siegesmund, ...
Slates are internationally known as roof and façade-cladding material since prehistoric times. Th... more Slates are internationally known as roof and façade-cladding material since prehistoric times. The methods required to mine and manufacture these dimensional stones are relatively simple in comparison to those utilized in granitic dimensional stones. This has led to a worldwide rentable commercialization of slate in the last centuries and also to the development of characteristic cultural landscapes. In Uruguay several slates are mined and used in architecture, especially as façade cladding and floor slabs. The most important slates regarding their production and utilization are the dolomitic slates. These dolomitic slates are associated with the Neoproterozoic thrust and fold belt of the Dom Feliciano belt. Representative samples have been geochemically and petrographically characterized, as well as petrophysically and petromechanically analyzed. The petrophysical and petromechanical properties were investigated in a very systematic way with respect to the new European standards, showing values comparable to those registered for internationally known slates. Detailed structural and deposit analysis were carried out in Uruguay in order to evaluate the dolomitic slate deposits. The slates are linked to calc-silicate strata in a greenschist facies volcano-sedimentary sequence and the deposits are located in the limb of a regional fold, where bedding and cleavage are parallel. The main lithotype is a layered and fine-grained dolomitic slate with a quite diverse palette of colors: light and dark green, gray, dark gray, reddish and black. The mined slate is split into slabs 0.5-2 cm thick. In the past, the average production in Uruguay was around 4,000 tons/year and a historical maximum of 13,000 tons was reached in 1993 (Oyhantçabal et al. in Z dt Ges Geowiss 158(3):417-428, 2007). The oscillations in the regional demand were the cause of several flourishing and decay cycles in the activity, but our investigation shows a considerable volume of indicated resources and therefore a very good potential.
Dimensional stones with a black color occupy a prominent place on the international market. Urugu... more Dimensional stones with a black color occupy a prominent place on the international market. Uruguayan dolerite dikes of andesitic and andesitic-basaltic composition are mined for commercial blocks of black dimensional stones. A total of 16 dikes of both compositions were studied and samples collected for geochemical and petrographical analysis. Color measurements were performed on different black dimensional stones in order to compare them with the Uruguayan dolerites. Samples of the two commercial varieties (Absolute Black and Moderate Black) were obtained for petrophysical analysis (e.g. density, porosity, uniaxial compressive strength, tensile strength, etc.). Detailed structural analyses were performed in several quarries. Geochemistry and petrography determines the intensity of the black color. The Uruguayan dolerite Absolute Black is the darkest black dimensional stone analyzed in this study. The petrophysical properties of Uruguayan dolerites make them one of the highest quality black dimensional stones. Structural analyses show that five joint sets have been recognized: two sub-vertical joints, one horizontal and two diagonal. These joint sets are one of the most important factors that control the deposits, since they control the block size distribution and the amount of waste material.
In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There i... more In Uruguay commercial granite varieties comprise mafic rocks, granitoids, and syenitoids. There is a long tradition in Uruguay, as well as worldwide, of using dimensional stones in architecture and art, specially granitic ones. Some of the present applications of these dimensional stones are as façade cladding, countertops, and outdoor and indoor floor slabs. The color spectrum of the Uruguayan granitic dimensional stones varies from black to light gray, covering a wide variety of red and pink and minor greenish-gray. The décor of these granitic dimensional stones is mainly determined by their fabric, fundamentally the grain size and the color distribution between the different minerals that compose the rocks. In the present research the most important commercial granites were sampled to analyze their petrography and petrophysical properties. A detailed structural analysis has been performed in several deposits, as well as the application of the software 3D Block Expert for modeling the possible raw block size distribution. Other factors controlling the mining viability of the deposits were also studied (e.g., homogeneity/heterogeneity of color and décor) and the possible reserves were calculated.