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Fluorcalciomicrolite
A valid IMA mineral species
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About Fluorcalciomicrolite
Formula:
(Ca,Na)2(Ta,Nb)2O6F
Colour:
Colourless
Lustre:
Adamantine, Resinous
Hardness:
4 - 5
Specific Gravity:
6.160 (Calculated)
Crystal System:
Isometric
Member of:
Name:
Named according to convention, for its dominant fluorine and calcium content, and for its relationship to other microlite group minerals.
Unique combination of elements. The (Ca,Na)-analogue of fluornatromicrolite. The Ta analogue of fluorcalciopyrochlore.
Unique Identifiers
Mindat ID:
40354
Long-form identifier:
mindat:1:1:40354:0
IMA Classification of Fluorcalciomicrolite
Approved
IMA Formula:
(Ca,Na)2Ta5+2O6F
Approval year:
2012
First published:
2013
Classification of Fluorcalciomicrolite
4.DH.15
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
H : With large (+- medium-sized) cations; sheets of edge-sharing octahedra
4 : OXIDES (Hydroxides, V[5,6] vanadates, arsenites, antimonites, bismuthites, sulfites, selenites, tellurites, iodates)
D : Metal: Oxygen = 1:2 and similar
H : With large (+- medium-sized) cations; sheets of edge-sharing octahedra
Mineral Symbols
As of 2021 there are now IMA–CNMNC approved mineral symbols (abbreviations) for each mineral species, useful for tables and diagrams.
| Symbol | Source | Reference for Standard |
|---|---|---|
| Fcmic | IMA–CNMNC | Warr, L.N. (2021). IMA–CNMNC approved mineral symbols. Mineralogical Magazine, 85(3), 291-320. doi:10.1180/mgm.2021.43 |
Physical Properties of Fluorcalciomicrolite
Adamantine, Resinous
Transparency:
Translucent
Colour:
Colourless
Streak:
White
Hardness:
4 - 5 on Mohs scale
Tenacity:
Brittle
Cleavage:
None Observed
Fracture:
Conchoidal
Density:
6.160 g/cm3 (Calculated)
Optical Data of Fluorcalciomicrolite
Type:
Isotropic
RI values:
n = 1.992
Surface Relief:
Very High (positive)
Relative to Canada balsam mounting medium (n ≈ 1.537).
Relative to Canada balsam mounting medium (n ≈ 1.537).
This shows the grain boundary and Becke line effect under plane-polarised
light, based on the contrast between this mineral's average refractive
index and the mounting medium. It does not take into account mineral
colouration.
In focus
Chemistry of Fluorcalciomicrolite
Mindat Formula:
(Ca,Na)2(Ta,Nb)2O6F
Element Weights:
Common Impurities:
Na,Nb,OH
Crystallography of Fluorcalciomicrolite
Crystal System:
Isometric
Class (H-M):
m3m(4/m32/m) - Hexoctahedral
Space Group:
Fd3m
Cell Parameters:
a = 10.4191(6) Å
Unit Cell V:
1131.07 ų
Z:
8
Twinning:
Not observed
Harding Mine, Picuris District, Taos County, New Mexico, USA