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Gajardoite

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About GajardoiteHide

Formula:
KCa0.5As3+4O6Cl2 · 5H2O
Lustre:
Vitreous
Hardness:
Specific Gravity:
2.64
Crystal System:
Hexagonal
Isostructural with:
New structure type. Unique combination of elements. Structurally related to torrecillasite. Compare russoite (also As2O3-containing species).

There are two types of layers in the structure: (1) KAs4O6Cl2, built of two neutral As2O3 sheets, with K cations between and Cl cations outside them (lucabindiite has identical layer); (2) edge-sharing sheet built of Ca(H2O)6 trigonal pyramids, with hexagonal cavities occupied by isolated H2O molecules.


Classification of GajardoiteHide

Approved
Approval Year:
2015
First Published:
2016

Physical Properties of GajardoiteHide

Vitreous
Transparency:
Transparent
Streak:
White
Hardness:
1½ on Mohs scale
Comment:
ca. 1.5
Tenacity:
Brittle
Cleavage:
Perfect
{001}
Fracture:
Irregular/Uneven
Density:
2.64 g/cm3 (Measured)    2.676 g/cm3 (Calculated)

Optical Data of GajardoiteHide

Type:
Uniaxial (-)
RI values:
nω = 1.780() nε = 1.570(5)
Max Birefringence:
δ = 0.210
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High

Chemical Properties of GajardoiteHide

Formula:
KCa0.5As3+4O6Cl2 · 5H2O
IMA Formula:
KCa0.5As3+4O6Cl2 · 5H2O
Common Impurities:
(Na,Mg)

Crystallography of GajardoiteHide

Crystal System:
Hexagonal
Class (H-M):
6/mmm (6/m 2/m 2/m) - Dihexagonal Dipyramidal
Space Group:
P6/mmm
Setting:
P6/mmm
Cell Parameters:
a = 5.2558(8) Å, c = 15.967(2) Å
Ratio:
a:c = 1 : 3.038
Unit Cell V:
381.96 ų
Z:
1
Morphology:
Hexagonal plates, up to ca. 100 x 5 μm, forming subparallel rosette-like intergrowths

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
16.00(100)
5.31(48)
3.466(31)
3.013(44)
2.624(51)
2.353(36)
1.845(21)
1.460(17)

Type Occurrence of GajardoiteHide

General Appearance of Type Material:
Hexagonal plates
Place of Conservation of Type Material:
Co-type material is deposited in the mineralogical collections of the Natural History Museum of Los Angeles County, 900 Exposition Boulevard, Los Angeles, CA 90007, USA, catalogue numbers 65585, 65586 and 65587
Associated Minerals at Type Locality:

Synonyms of GajardoiteHide

Other InformationHide

Notes:
Very slowly soluble in water; slowly soluble in dilute HCl (room temperature).
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 GajardoiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Kampf, A.R., Nash, B., Dini, M. and Molina Donoso, A.A. (2015) Gajardoite, IMA 2015-040. CNMNC Newsletter No. 26, August 2015, page 947; Mineralogical Magazine: 79: 941-947.
Kampf, A.R., Nash, B.P., Dini, M. Molina Donoso, A.A. (2016): Gajardoite, KCa0.5As3+4O6Cl2·5H2O, a new mineral related to lucabindiite and torrecillasite from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine: 80: 1265-1272.

Internet Links for GajardoiteHide

Localities for GajardoiteHide

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 (TL)
 
  • Tarapacá Region
    • Iquique Province
      • Salar Grande
Kampf, A.R., Nash, B., Dini, M. and Molina Donoso, A.A. (2015) Gajardoite, IMA 2015-040. CNMNC Newsletter No. 26, August 2015, page 947; Mineralogical Magazine, 79, 941-947 ; Kampf, A.R., Nash, B.P., Dini, M. Molina Donoso, A.A. (2016): Gajardoite, KCa0.5As3+4O6Cl2·5H2O, a new mineral related to lucabindiite and torrecillasite from the Torrecillas mine, Iquique Province, Chile. Mineralogical Magazine, 80, 1265-1272.
Mineral and/or Locality  
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