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Tarapacáite

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Formula:
K2[CrO4]
System:
Orthorhombic
Colour:
Bright yellow, ...
Name:
Named after its discovery locality, Tocopilla Pampa, Tarapacá, Chile.
Isostructural with:
Easily synthesised (compare lopezite).

Classification of Tarapacáite

Valid - first described prior to 1959 (pre-IMA) - "Grandfathered"
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
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First Recorded Occurrence of Tarapacáite

Year of Discovery:
1878
Associated Minerals at First Recorded Locality:

Physical Properties of Tarapacáite

Diaphaneity (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.

Crystallography of Tarapacáite

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

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.
Surface Relief:
High
Dispersion:
r > v weak

Chemical Properties of Tarapacáite

Formula:
K2[CrO4]
Essential elements:
All elements listed in formula:

Relationship of Tarapacáite to other Species

7.FA.10ChromatiteCa[CrO4]
7.FA.15HashemiteBa(Cr,S)O4
7.FA.20CrocoitePb(CrO4)
27.2.2LópeziteK2[Cr2O7]
27.2.3ChromatiteCa[CrO4]
27.2.4HashemiteBa(Cr,S)O4
27.2.5CrocoitePb(CrO4)
27.2.6PhoenicochroitePb2(CrO4)O
27.2.7SantanaitePb11(CrO4)O12
27.2.8IranitePb10Cu(CrO4)6(SiO4)2(OH)2
27.2.9HemihedritePb10Zn(CrO4)6(SiO4)2(F,OH)2

Other Names for Tarapacáite

Name in Other Languages:

Other Information

Other Information:
Readily soluble in water.
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.

References for Tarapacáite

Reference List:
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 Tarapacáite

Localities for Tarapacáite

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.
(TL) indicates type locality for a valid mineral species. (FRL) indicates first recorded locality for everything else. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.
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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