Segerstromite
A valid IMA mineral species
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About Segerstromite
Formula:
Ca3(As5+O4)2[As3+(OH)3]2
Colour:
Colorless
Lustre:
Vitreous
Hardness:
4½
Specific Gravity:
3.46
Crystal System:
Isometric
Name:
Named in honor of Kenneth Segerstrom (1909–1992), geologist with the U.S. Geological Survey, working the in the U.S., Mexico, and Chile. He spent several years working and mapping in the Atacama Region, including the Cobriza mine - the type locality.
The first known crystalline compound that contains the As3+(OH)3 arsenite molecule.
Unique Identifiers
Mindat ID:
45988
Long-form identifier:
mindat:1:1:45988:6
IMA Classification of Segerstromite
Approved
Approval year:
2014
First published:
2018
Type description reference:
Classification of Segerstromite
8.BO.60
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
O : With only large cations, (OH, etc.):RO4 about 1:1
8 : PHOSPHATES, ARSENATES, VANADATES
B : Phosphates, etc., with additional anions, without H2O
O : With only large cations, (OH, etc.):RO4 about 1:1
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 |
|---|---|---|
| Ssr | 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 Segerstromite
Vitreous
Transparency:
Transparent
Colour:
Colorless
Comment:
in transmitted light
Streak:
White
Hardness:
4½ on Mohs scale
Comment:
~4.5
Tenacity:
Brittle
Cleavage:
None Observed
Parting:
None observed
Fracture:
None observed
Density:
3.46 g/cm3 (Measured) 3.44(3) g/cm3 (Calculated)
Optical Data of Segerstromite
Type:
Isotropic
RI values:
n = 1.731(5)
Birefringence:
Isotropic minerals have no birefringence
Surface Relief:
High
Chemistry of Segerstromite
Mindat Formula:
Ca3(As5+O4)2[As3+(OH)3]2
Element Weights:
Elements listed:
Crystallography of Segerstromite
Crystal System:
Isometric
Class (H-M):
2 3 - Tetartoidal
Space Group:
I21 3
Setting:
I21 3
Cell Parameters:
a = 10.7627(2) Å
Unit Cell V:
1246.71 ų
Z:
4
Morphology:
As tetrahedra, dodecahedra and in blocky aggregates.
Twinning:
None observed
X-Ray Powder Diffraction
Powder Diffraction Data:
| d-spacing | Intensity |
|---|---|
| 4.351 Å | (34) |
| 3.775 Å | (25) |
| 3.389 Å | (82) |
| 3.104 Å | (33) |
| 2.875 Å | (100) |
| 2.111 Å | (45) |
| 1.905 Å | (27) |
| 1.748 Å | (34) |
Reference:
Geological Environment
Paragenetic Mode(s):
| Paragenetic Mode | Earliest Age (Ga) |
|---|---|
| Stage 7: Great Oxidation Event | <2.4 |
| 47a : [Near-surface hydration of prior minerals] | |
| 47d : [Arsenates, antimonates, selenates, bismuthinates] |
Type Occurrence of Segerstromite
General Appearance of Type Material:
A secondary mineral, as tetrahedra, dodecahedra (up to 0.50 × 0.50 × 0.50 mm), or in blocky aggregates.
Place of Conservation of Type Material:
Cotype material is deposited in the collections of the Mineral Museum of the University of Arizona, Tucson, Arizona, USA, catalogue number 19800 and with the RRUFF Project, deposition number R130753.
Empirical Formula of Type Material:
Ca2.98(AsO4)2.00[As(OH)3]2.00
Associated Minerals at Type Locality:
Reference:
Synonyms of Segerstromite
Other Language Names for Segerstromite
Dutch:Segerstromiet
German:Segerstromit
Common Associates
Associations Based on Photo Data:
Related Minerals - Strunz-mindat Grouping
| 8.BO. | Ariegilatite | BaCa12(SiO4)4(PO4)2F2O |
| 8.BO. | Aravaite | Ba2Ca18(SiO4)6(PO4)3(CO3)F3O |
| 8.BO. | Theuerdankite | Ag3AsO4 |
| 8.BO.05 | Nacaphite | Na2Ca(PO4)F |
| 8.BO.10 | Petitjeanite | Bi3(PO4)2O(OH) |
| 8.BO.10 | Schumacherite | Bi3(VO4)2O(OH) |
| 8.BO.10 | Preisingerite | Bi3(AsO4)2O(OH) |
| 8.BO.15 | Hechtsbergite | Bi2(VO4)O(OH) |
| 8.BO.15 | Smrkovecite | Bi2(PO4)O(OH) |
| 8.BO.15 | Atelestite | Bi2(AsO4)O(OH) |
| 8.BO.20 | Sahlinite | Pb14(AsO4)2O9Cl4 |
| 8.BO.20 | Kombatite | Pb14(VO4)2O9Cl4 |
| 8.BO.25 | Heneuite | CaMg5(CO3)(PO4)3(OH) |
| 8.BO.30 | Nefedovite | Na5Ca4(PO4)4F |
| 8.BO.35 | Kuznetsovite | [Hg2]2+Hg2+[AsO4]Cl |
| 8.BO.40 | Artsmithite | [Hg2]2+2Al(PO4)1.74(OH)1.78 |
| 8.BO.45 | Schlegelite | Bi7(AsO4)3(MoO4)2O4 |
| 8.BO.50 | Hereroite | [Pb32(O,◻)21](AsO4)2[(Si,As,V,Mo)O4]2Cl10 |
| 8.BO.50 | Erikjonssonite | (Pb32O21)[(V,Si,Mo,As)O4]4Cl9 |
| 8.BO.55 | Rudabányaite | (Ag2Hg2)(AsO4)Cl |
| 8.BO.65 | Wiklundite | Pb2(Mn2+,Zn)3(Fe3+,Mn2+)2(Mn2+,Mg)19(As3+O3)2[(Si,As5+)O4]6(OH)18Cl6 |
Other Information
Notes:
Insoluble in water or hydrochloric acid
Health Risks:
No information on health risks for this material has been entered into the database. You should always treat mineral specimens with care.
Internet Links for Segerstromite
mindat.org URL:
https://www.mindat.org/min-45988.html
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References for Segerstromite
Reference List:
Williams, P. A., Hatert, F., Pasero, M., Mills, S. J. (2014) New minerals and nomenclature modifications approved in 2014, CNMNC Newsletter No 20. Mineralogical Magazine, 78 (3) 549-558 doi:10.1180/minmag.2014.078.3.05
Localities for Segerstromite
Showing 1 localities.
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 (TL) | |
| Williams et al. (2014) +2 other references |
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Cobriza mine, Chinchado-Sacramento mining district, Pabellón, Tierra Amarilla, Copiapó Province, Atacama, Chile