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Tarapacáite

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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:
Easily synthesised (compare lopezite).


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Classification of TarapacáiteHide

Approved, 'Grandfathered' (first described prior to 1959)
7.FA.05

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
27.2.1

27 : Sulphites, Chromates, Molybdates and Tungstates
2 : Chromates

Physical Properties of TarapacáiteHide

Transparency:
Transparent
Colour:
Bright yellow, yellow-orange
Cleavage:
Distinct/Good
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 TarapacáiteHide

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.
Surface Relief:
High
Dispersion:
r > v weak

Chemical Properties of TarapacáiteHide

Formula:
K2(CrO4)
IMA Formula:
K2CrO4

Crystallography of TarapacáiteHide

Crystal System:
Orthorhombic
Class (H-M):
mmm (2/m 2/m 2/m) - Dipyramidal
Cell Parameters:
a = 7.66 Å, b = 10.39 Å, c = 5.91 Å
Ratio:
a:b:c = 0.737 : 1 : 0.569
Unit Cell V:
470.36 ų (Calculated from Unit Cell)
Morphology:
Crystals thick tabular {001}.
Twinning:
Twinning on {110} producing pseudo-hexagonal twins analogous to aragonite.

Type Occurrence of TarapacáiteHide

Other Language Names for TarapacáiteHide

Related Minerals - Nickel-Strunz GroupingHide

7.FA.10ChromatiteCaCr6+O4Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
7.FA.15HashemiteBa(CrO4)Orth. mmm (2/m 2/m 2/m) : Pnma
7.FA.20CrocoitePb(CrO4)Mon. 2/m : P21/b

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

27.2.2LópeziteK2Cr2O7Tric. 1 : P1
27.2.3ChromatiteCaCr6+O4Tet. 4/mmm (4/m 2/m 2/m) : I41/amd
27.2.4HashemiteBa(CrO4)Orth. mmm (2/m 2/m 2/m) : Pnma
27.2.5CrocoitePb(CrO4)Mon. 2/m : P21/b
27.2.6PhoenicochroitePb2(CrO4)OMon.
27.2.7SantanaitePb11(CrO4)O12Hex. 6 2 2 : P63 2 2
27.2.8IranitePb10Cu(CrO4)6(SiO4)2(OH)2Tric.
27.2.9HemihedritePb10Zn(CrO4)6(SiO4)2(OH)2Tric.

Other InformationHide

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.

References for TarapacáiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Raimondi, A. (1878) Minéraux du Pérou: Catalogue raisonné d’une collection des principaux types minéraux de la République. 336pp., Paris: 274.
Gossner (1904) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 39: 166.
Brendler (1923) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 58: 445 (quotes Mitscherlich (1830) Annalen der Physik, Halle, Leipzig: 18: 169).
Zachariasen and Ziegler (1931) Zeitschrift für Kristallographie, Mineralogie und Petrographie, Leipzig: 80: 164.
Larsen, E.S. and Berman, H. (1934) The Microscopic Determination of the Nonopaque Minerals, Second edition, USGS Bulletin 848: 192.
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II. John Wiley and Sons, Inc., New York, 7th edition, revised and enlarged, 1124 pp.: 644.
Acta Crystallographica (1972): B28: 2845.

Internet Links for TarapacáiteHide

Localities for TarapacáiteHide

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 locality has map coordinates listed. - This locality has estimated coordinates. ⓘ - Click for 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 (eg from pseudomorphs.)

All localities listed without proper references should be considered as questionable.
Chile
 
  • Antofagasta Region
    • Antofagasta Province
No reference listed
    • Tocopilla Province
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 645; Acta Cryst. B28 (1972), 2843; J.W. Anthony, R.A. Bideaux, K.W. Bladh, M.C. Nichols: Handbook of Mineralogy, Vol. V (2003)
Palache, C., Berman, H., & Frondel, C. (1951), The System of Mineralogy of James Dwight Dana and Edward Salisbury Dana, Yale University 1837-1892, Volume II: 646; Anthony, Bideaux, Bladh, Nichols (2003) Handbook of Mineralogy - Vol. 5.
J.W. Anthony, R.A. Bideaux, K.W. Bladh, M.C. Nichols: Handbook of Mineralogy, Vol. V (2003)
  • Tarapacá Region
    • El Tamarugal Province
J.W. Anthony, R.A. Bideaux, K.W. Bladh, M.C. Nichols: Handbook of Mineralogy, Vol. V (2003); American Mineralogist: 79: 1003-1008.
Mineral and/or Locality  
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