Marcobaldiite (original) (raw)

A valid IMA mineral species

Formula:

Pb12(Sb3As2Bi)Σ6S21

Specific Gravity:

6.56 (Calculated)

Name:

Named in honour of the amateur mineralogist Marco Baldi (b. 1944) for his contribution to the knowledge of the mineralogy of the pyrite ± baryte ± iron oxide ore deposits from southern Apuan Alps.

A N = 3.5 homologue of the jordanite homologous series, characterized by the 1:1 alternation of two kinds of layers of distorted octahedra, three- and four-octahedra thick, i.e. of the kirkiite and jordanite types, respectively. Layers are connected by one atomic layer of three bicapped trigonal prismatic Pb atoms and one triangular pyramidal As atom in split position (Biagioni et al. 2018).

Seems to be the Sb3As2Bi analogue of arsenmarcobaldiite. Likely unique as a sulphosalt with Sb, As and Bi being all required.

Discovered from a single specimen (Biagioni et al. 2018).

Unique IdentifiersHide

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Long-form identifier:

mindat:1:1:47600:5

f9c7cd67-1847-4b5c-b6dc-9357f0d69ce8

IMA Classification of MarcobaldiiteHide

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IMA Formula:

Pb12(Sb3As2Bi)Σ6S21

Type description reference:

Biagioni, Cristian, Pasero, Marco, Moëlo, Yves, Zaccarini, Federica, Paar, Werner H. (2018) Lead-antimony sulfosalts from Tuscany (Italy) XXII. Marcobaldiite, ∼Pb12(Sb3As2Bi)Σ6S21, a new member of the jordanite homologous series from the Pollone mine, Valdicastello Carducci. European Journal of Mineralogy, 30 (3) 581-592 doi:10.1127/ejm/2018/0030-2710

Classification of MarcobaldiiteHide

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2.JB.30a

2 : SULFIDES and SULFOSALTS (sulfides, selenides, tellurides; arsenides, antimonides, bismuthides; sulfarsenites, sulfantimonites, sulfbismuthites, etc.)
J : Sulfosalts of PbS archetype
B : Galena derivatives, with Pb

Mineral SymbolsHide

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As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.

Physical Properties of MarcobaldiiteHide

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Hardness:

VHN15=170 - 195 kg/mm2 - Vickers

Fracture:

Irregular/Uneven

Density:

6.56 g/cm3 (Calculated)

Optical Data of MarcobaldiiteHide

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Anisotropism:

Distinct with grey to bluish-grey rotation tints

Reflectivity:

Graph shows reflectance levels at different wavelengths (in nm). Top of box is 100%. Peak reflectance is 40.1%.
R1 shown in black, R2 shown in red

Colour in reflected light:

White under the ore microscope

Internal Reflections:

Not observed

Chemistry of MarcobaldiiteHide

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Mindat Formula:

Pb12(Sb3As2Bi)Σ6S21

Crystallography of MarcobaldiiteHide

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Cell Parameters:

a = 8.9248(9) Å, b = 29.414(3) Å, c = 8.5301(8) Å
α = 98.336(5)°, β = 118.175(5)°, γ = 90.856(5)°

Ratio:

a:b:c = 0.303 : 1 : 0.29

Twinning:

Polysynthetic lamellar twinning is common.

X-Ray Powder DiffractionHide

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Powder Diffraction Data:

Geological EnvironmentHide

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Type Occurrence of MarcobaldiiteHide

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General Appearance of Type Material:

A black blocky prismatic crystal (up to 1 cm in size).

Place of Conservation of Type Material:

collections of the Museo di Storia Naturale, Università di Pisa, Via Roma 79, Calci (Pisa), Italy (catalogue number 19709).

Empirical Formula of Type Material:

Pb11.98(4)Sb2.90(3)As2.33(3)Bi0.79(1)S20.80(20)

Chemical Analysis of Type Material:

Geological Setting of Type Material:

A quartz vein embedded in tourmaline-bearing schist .

Associated Minerals at Type Locality:

Reference:

Biagioni, C., Pasero, M., Moëlo, Y., Zaccarini, F., Paar, W.H. (2018) Lead-antimony sulfosalts from Tuscany (Italy). XXII. Marcobaldiite, ∼Pb12(Sb3As2Bi)Σ6S21, a new member of the jordanite homologous series from the Pollone mine, Valdicastello Carducci. European Journal of Mineralogy, 30: 581-592

Synonyms of MarcobaldiiteHide

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Relationship of Marcobaldiite to other SpeciesHide

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Other Members of this group:

Related Minerals - Strunz-mindat GroupingHide

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Other InformationHide

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Health Risks:

No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

Internet Links for MarcobaldiiteHide

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References for MarcobaldiiteHide

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Reference List:

Biagioni, Cristian, Pasero, Marco, Moëlo, Yves, Zaccarini, Federica, Paar, Werner H. (2018) Lead-antimony sulfosalts from Tuscany (Italy) XXII. Marcobaldiite, ∼Pb12(Sb3As2Bi)Σ6S21, a new member of the jordanite homologous series from the Pollone mine, Valdicastello Carducci. European Journal of Mineralogy, 30 (3) 581-592 doi:10.1127/ejm/2018/0030-2710

Localities for MarcobaldiiteHide

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This map shows a selection of localities that have latitude and longitude coordinates recorded. Click on the symbol to view information about a locality. The symbol next to localities in the list can be used to jump to that position on the map.

Locality ListHide

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- This locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for references and further information on this occurrence. ? - Indicates mineral may be doubtful at this locality. - Good crystals or important locality for species. - World class for species or very significant. (TL) - Type Locality for a valid mineral species. (FRL) - First Recorded Locality for everything else (eg varieties). Struck out - Mineral was erroneously reported from this locality. Faded * - Never found at this locality but inferred to have existed at some point in the past (e.g. from pseudomorphs).

All localities listed without proper references should be considered as questionable.