Chiavennite (original) (raw)

A valid IMA mineral species

About ChiavenniteHide

This section is currently hidden. Click the show button to view.

Formula:

CaMnBe2Si5O13(OH)2 · 2H2O

from Grice et al. (2016): Ca1-2(Mn,Fe)Si5Be2O13(OH)2.2H2O

Colour:

Pale orange-yellow

Crystal System:

Monoclinic

Name:

Named by Mirella Bondi, William L. Griffin, Vittorio Mattioli, and Annibale Mottana in 1983 for the type locality of Chiavenna, Italy.

Co-Type Localities:

ⓘ Unnamed pegmatite, Chiavenna, Sondrio Province, Lombardy, Italy
ⓘ Chiavennite dike, Blåfjell (E18 roadcuts), Kokkersvold - Blåfjell E18 roadcuts, Langangen, Porsgrunn, Telemark, Norway

Closely related to Ferrochiavennite, which is its Fe analogue. See also the related tvedalite and another chemically close mineral, harstigite. Re-investigations of Chiavennite from the TL indicate that at room temperature chiavennite is monoclinic with spacegroup _P_21/c; the mineral becomes orthorhombic (Pbcn) upon dehydration due to destruction of water(extraframework)-oxygen(cavity walls) hydrogen bonds (Cametti & Armbruster 2015).

The structure is described as an interrupted framework with four-connected SiO4 and three-connected BeO4 tetrahedra, the latter closely associated with H atoms. There are 9-, 6-, 5- and 4-fold rings in it. Calcium may exist in a single site, or in two sites, of which the second one is partially occupied.

The history of the discovery of chiavennite
Chiavennite was first discovered in 1970 by the Norwegian mineralogist Reidar Åmli in a syenite pegmatite in the Heia Quarry, Tvedalen, Larvik, Vestfold, Norway. A qualitative analysis (by Per Chr. Sæbø) showed it to be a possible new mineral, a Ca-Mn-Be silicate, but due to the scarcity of the material, no further investigation was made. A few years later, in 1974, Arne Åsheim found identical material from another locality in the same area, at Blåfjell (E 18 roadcuts), Kokkersvold, Porsgrunn, Telemark and a new research on the material were initiated. Independently, the same mineral was discovered in an Italian locality, Tannon, Chiavenna, Valchiavenna, Sondrio Province, Lombardy.
The Norwegian research group submitted their description with the complete data to the IMA CNMMN, on the March 4. 1981, but it turned out that the Italians, independently, had submitted their description only a few days earlier. The new mineral was approved by IMA after a joint submission of the data from the Italian and Norwegian groups.
The mineral was named chiavennite after the Italian locality, since the Italian proposal was submitted first. Descriptions on both the Italian and the Norwegian minerals were published in 1983, in the same issue of the American Mineralogist (Bondi et al. 1983, Raade et al. 1983, Raade 1996, Larsen 2001, Ciriotti et al. 2009).

Unique IdentifiersHide

This section is currently hidden. Click the show button to view.

Long-form identifier:

mindat:1:1:1002:9

2c276d2a-9a24-4735-855f-188c2dbdba6c

IMA Classification of ChiavenniteHide

This section is currently hidden. Click the show button to view.

IMA Formula:

CaMn2+(BeOH)2Si5O13 · 2H2O

Classification of ChiavenniteHide

This section is currently hidden. Click the show button to view.

9.GF.25

9 : SILICATES (Germanates)
G : Tektosilicates with zeolitic H2O; zeolite family
F : Other Rare Zeolites

70.5.1.1

70 : INOSILICATES Column or Tube Structures
5 : Column or Tube Structures with chains linked by Be

14.3.18

14 : Silicates not Containing Aluminum
3 : Silicates of Be

Mineral SymbolsHide

This section is currently hidden. Click the show button to view.

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

Physical Properties of ChiavenniteHide

This section is currently hidden. Click the show button to view.

Colour:

Pale orange-yellow

Cleavage:

Perfect
Good to perfect cleavages along {100}, {010}, and {001}.

Density:

2.64 g/cm3 (Measured) 2.657 g/cm3 (Calculated)

Optical Data of ChiavenniteHide

This section is currently hidden. Click the show button to view.

RI values:

_n_α = 1.596(2) _n_β = 1.600(2) _n_γ = 1.618(2)

2V:

Measured: 50° , Calculated: 52°

δ = 0.022

Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.

Optical Extinction:

X = a, Y = b, Z = c.

Comments:

X = colorless to pale yellow; Z = yellow-orange.

Chemistry of ChiavenniteHide

This section is currently hidden. Click the show button to view.

Mindat Formula:

CaMnBe2Si5O13(OH)2 · 2H2O

from Grice et al. (2016): Ca1-2(Mn,Fe)Si5Be2O13(OH)2.2H2O

Common Impurities:

Al,Fe,Mg,Ca,Na,K,F,C

Chemical AnalysisHide

This section is currently hidden. Click the show button to view.

Empirical formulas:

Sample references:

Crystallography of ChiavenniteHide

This section is currently hidden. Click the show button to view.

Crystal System:

Monoclinic

Class (H-M):

2/m - Prismatic

Cell Parameters:

a = 8.7466(3) Å, b = 4.8972(3) Å, c = 31.3160(16) Å
β = 90.128(4)°

Ratio:

a:b:c = 1.786 : 1 : 6.395

Morphology:

Crystals from the TL are showing a flat pseudohexagonal habit. From Larvik Plutonic Complex (Langesundsfjorden area), Norway: Spherulitic aggregates concisting of spear-shaped crystals, flattened on {010}, terminated by the orthorhombic pyramid {161}.

Twinning:

Common, on {100}.

Comment:

Previously reported to be orthorhombic; unit cell parameters for the orthorhombic dehydrated phase, i.e., at 425oC, of the Pbcn cell, transformed in (non-standard) Pnca setting: a=8.6795(15), b=4.9017(10), c=31.513(6).

Crystal StructureHide

This section is currently hidden. Click the show button to view.

Load
Unit Cell |Unit Cell Packed
2x2x2 |3x3x3 |4x4x4

Show
Big Balls |Small Balls |Just Balls |Spacefill
Polyhedra Off |Si Polyhedra |All Polyhedra
Remove metal-metal sticks

Display Options
Black Background |White Background
Perspective On |Perspective Off
2D |Stereo |Red-Blue |Red-Cyan

View
CIF File Best |x |y |z |a |b |c

Rotation
Stop |Start

Labels
Console Off |On |Grey |Yellow

CIF Raw Data - click here to close

X-Ray Powder DiffractionHide

This section is currently hidden. Click the show button to view.

Powder Diffraction Data:

Geological EnvironmentHide

This section is currently hidden. Click the show button to view.

Geological Setting:

Alkaline syenite pegmatites and granite pegmatites

Type Occurrence of ChiavenniteHide

This section is currently hidden. Click the show button to view.

Co-Type Localities:

ⓘ Unnamed pegmatite, Chiavenna, Sondrio Province, Lombardy, Italy
ⓘ Chiavennite dike, Blåfjell (E18 roadcuts), Kokkersvold - Blåfjell E18 roadcuts, Langangen, Porsgrunn, Telemark, Norway

General Appearance of Type Material:

As euhedral orange grains and as crusts coating beryl.

Place of Conservation of Type Material:

Mineralogical-Geological Museum, University of Oslo, Oslo, Norway, numbers 22090, 22091 (cotype).
Istituto di Mineralogia e Petrografia dell’Università, Cita Universitaria, Rome, Italy, number 24342 (type).
National Museum of Natural History, Washington, D.C., USA, number 159917.
Musée Géologique Cantonal, Lausanne, Switzerland, number MGL 90755 (type).

Empirical Formula of Type Material:

(Ca0.97Na0.05) Σ1.02Mn0.97(Be1.98Al0.03)Σ2.01(Si4.65Al0.35)Σ5.00O12.63(OH)2.37* 2.16H2O

Geological Setting of Type Material:

Alpine pegmatites (25-27 m.y.).

Associated Minerals at Type Locality:

Synonyms of ChiavenniteHide

This section is currently hidden. Click the show button to view.

Other Language Names for ChiavenniteHide

This section is currently hidden. Click the show button to view.

Relationship of Chiavennite to other SpeciesHide

This section is currently hidden. Click the show button to view.

Other Members of this group:

Common AssociatesHide

This section is currently hidden. Click the show button to view.

Associated Minerals Based on Photo Data:

Related Minerals - Strunz-mindat GroupingHide

This section is currently hidden. Click the show button to view.

Other InformationHide

This section is currently hidden. Click the show button to view.

Thermal Behaviour:

Continuous water loss up to ca. 452°C not associated with topological modification; at 250°C more than a single water molecule is lost, in association with LKCa lowering from 8 to 7.

Notes:

Insoluble in water, and in concentrated HCl, HNO3 and H2SO4.

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 ChiavenniteHide

This section is currently hidden. Click the show button to view.

References for ChiavenniteHide

This section is currently hidden. Click the show button to view.

Reference List:

Bondi, Mirella, Griffin, William L., Mattioli, Vittorio, Mottana, Annibale (1983) Chiavennite, CaMnBe2Si5O13(OH)2·2H2O, a new mineral from Chiavenna (Italy) American Mineralogist, 68 (5-6) 623-627

Raade, Gunnar, Åmli, Reidar, Mladeck, Micael H., Din, Victor K., Larsen, Alf Olav, Åsheim, Arne (1983) Chiavennite from syenite pegmatites in the Oslo Region, Norway. American Mineralogist, 68 (5-6) 628-633

Coombs, Douglas S., Alberti, Alberto, Armbruster, Thomas, Artioli, Gilberto, Colella, Carmine, Galli, Ermanno, Grice, Joel D., Liebau, Friedrich, Mandarino, Joseph A., Minato, Hideo, Nickel, Ernest H., Passaglia, Elio, Peacor, Donald R., Quartieri, Simona, Rinaldi, Romano, Ross, Malcolm I., Sheppard, Richard A., Tillmanns, Ekkehart, Vezzalini, Giovanna (1997) Recommended nomenclature for zeolite minerals; report of the Subcommittee on Zeolites of the International Mineralogical Association, Commission on New Minerals and Mineral Names. The Canadian Mineralogist, 35 (6) 1571-1606

Pezzotta, F., Guastoni, A., Forner, H., Demartin, F., Kristiansen, R. (2005) Découverte exceptionnelle de chiavennite associée à pezzottaite dans la pegmatite de Sakavalana, Mandrosonoro, Madagascar. Le Règne Minéral: 61: 25-28.

Localities for ChiavenniteHide

This section is currently hidden. Click the show button to view.

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

This section is currently hidden. Click the show button to view.

- 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.