Tarapacáite
A valid IMA mineral species - grandfathered
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About Tarapacáite
Coat of arms, Tarapacá, Chile
Formula:
K2(CrO4)
Colour:
Bright yellow, yellow-orange
Specific Gravity:
2.74
Crystal System:
Orthorhombic
Name:
Named after Tarapacá, Chile, a region that includes the discovery locality, Tocopilla Pampa.
Isostructural with:
Unique Identifiers
Mindat ID:
3891
Long-form identifier:
mindat:1:1:3891:7
GUID
(UUID V4):
(UUID V4):
b5146deb-2afe-41cb-bcc4-f918b66ed636
IMA Classification of Tarapacáite
Approved, 'Grandfathered' (first described prior to 1959)
First published:
1878
Classification of Tarapacáite
7.FA.05
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
A : Without additional anions
7 : SULFATES (selenates, tellurates, chromates, molybdates, wolframates)
F : Chromates
A : Without additional anions
Dana 7th ed.:
35.1.1.1
35.1.1.1
35 : ANHYDROUS CHROMATES
1 : A2XO4
35 : ANHYDROUS CHROMATES
1 : A2XO4
27.2.1
27 : Sulphites, Chromates, Molybdates and Tungstates
2 : Chromates
27 : Sulphites, Chromates, Molybdates and Tungstates
2 : Chromates
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 |
|---|---|---|
| Tpc | 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 Tarapacáite
Transparency:
Transparent
Colour:
Bright yellow, yellow-orange
Cleavage:
Distinct/Good
On {001} and {010}, distinct.
On {001} and {010}, distinct.
Density:
2.74 g/cm3 (Measured) 2.735 g/cm3 (Calculated)
Comment:
Measured value on artificial material.
Optical Data of Tarapacáite
Type:
Biaxial (-)
RI values:
nα = 1.687 nβ = 1.722 nγ = 1.731
2V:
Measured: 52° , Calculated: 52°
Max Birefringence:
δ = 0.044
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
r > v weak
Optical Extinction:
X = c; Y = a; Z = b.
Chemistry of Tarapacáite
Mindat Formula:
K2(CrO4)
Elements listed:
Crystallography of Tarapacáite
Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 7.662(1) Å, b = 10.391(1) Å, c = 5.919(1) Å
Ratio:
a:b:c = 0.737 : 1 : 0.57
Unit Cell V:
471.25 ų (Calculated from Unit Cell)
Z:
4
Morphology:
Crystals thick tabular {001}.
Twinning:
Twinning on {110} producing pseudo-hexagonal twins analogous to aragonite.
Comment:
Space group Pnam (synthetic).
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 3.078 Å | (100) |
| 2.988 Å | (75) |
| 2.960 Å | (40) |
| 2.479 Å | (25) |
| 2.286 Å | (25) |
| 2.599 Å | (22) |
| 2.570 Å | (21) |
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Near-surface Processes | |
| 25 : Evaporites (prebiotic) | |
| High-𝑇 alteration and/or metamorphism | |
| 33 : Minerals deposited by hydrothermal metal-rich fluids (see also [#12]) |
Type Occurrence of Tarapacáite
Place of Conservation of Type Material:
n.d.
Geological Setting of Type Material:
Nitate deposits.
Associated Minerals at Type Locality:
Reference:
Raimondi A (1878) Tarapacaïte (chromate de potasse), avec nitratine (nitrate de soude), mêlée avec de la terre ferrugineuse. in Minéraux du Pérou, Traduit de l'espagnol par J B H Martinet, A. Chaix (Paris) 274-278
Synonyms of Tarapacáite
Other Language Names for Tarapacáite
Related Minerals - Strunz-mindat Grouping
| 7.FA.10 | Chromatite | CaCr6+O4 |
| 7.FA.15 | Hashemite | BaCr6+O4 |
| 7.FA.20 | Crocoite | PbCr6+O4 |
Other Information
Notes:
Readily soluble in water.
Health Risks:
Chromate minerals contain the carcinogenic and mutagenic chromate ion. Always wash hands after handling. Avoid inhaling dust when handling or breaking. Never lick or ingest. Do not pour chromate-containing solutions down the drain.
Internet Links for Tarapacáite
mindat.org URL:
https://www.mindat.org/min-3891.html
Please feel free to link to this page.
Please feel free to link to this page.
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References for Tarapacáite
Localities for Tarapacáite
symbol to view information about a locality.
The Locality List
- 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).
All localities listed without proper references should be considered as questionable.
Chile | |
| |
| Palache et al. (1951) +2 other references |
| Palache et al. (1951) +1 other reference | |
| J.W. Anthony et al. (2003) | |
| Konnert et al. (1994) +1 other reference |
Israel | |
| Sharygin +7 other references |
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Tarapacá, Chile