IMPORTANT MESSAGE. We need your support now to keep mindat.org running. Click here to find out why.
Log InRegister
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreContact UsAdvertise on Mindat
Donate to MindatCorporate SponsorshipSponsor a PageSponsored PagesMindat AdvertisersAdvertise on Mindat
Learning CenterWhat is a mineral?The most common minerals on earthInformation for Educators
Minerals by PropertiesMinerals by ChemistryAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDLocalities Near MeSearch ArticlesSearch GlossaryMore Search Options
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
StatisticsThe ElementsUsersBooks & MagazinesMineral MuseumsMineral Shows & EventsThe Mindat DirectoryDevice Settings
Photo SearchPhoto GalleriesNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day Gallery

Geminite

This page is currently not sponsored. Click here to sponsor this page.
Hide all sections | Show all sections

About GeminiteHide

Formula:
Cu(HAsO4) · H2O
Colour:
Light green to sea green
Lustre:
Vitreous
Hardness:
3 - 3½
Specific Gravity:
3.70
Crystal System:
Triclinic
Name:
Named by H. Sarp and P. Perroud in 1990. The name is derived from the Latin gemini, meaning twins, for the twinning observed in the mineral.
This page provides mineralogical data about Geminite.


Classification of GeminiteHide

Approved
Approval Year:
1988
8.CB.30

8 : PHOSPHATES, ARSENATES, VANADATES
C : Phosphates without additional anions, with H2O
B : With only medium-sized cations, RO4:H2O = 1:1
40.5.12.1

40 : HYDRATED NORMAL PHOSPHATES,ARSENATES AND VANADATES
5 : AXO4·xH2O
20.1.7

20 : Arsenates (also arsenates with phosphate, but without other anions)
1 : Arsenates of Cu

Physical Properties of GeminiteHide

Vitreous
Transparency:
Transparent
Colour:
Light green to sea green
Streak:
Pale green
Hardness:
3 - 3½ on Mohs scale
Cleavage:
Perfect
{001}
Fracture:
Irregular/Uneven
Density:
3.70(2) g/cm3 (Measured)    3.71 g/cm3 (Calculated)

Optical Data of GeminiteHide

Type:
Biaxial (+)
RI values:
nα = 1.656 nβ = 1.692 nγ = 1.770
2V:
Measured: 75° , Calculated: 72°
Max Birefringence:
δ = 0.114
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
High
Dispersion:
weak
Pleochroism:
Weak
Comments:
α = β = colorless
γ = pale green to pale gray

Chemical Properties of GeminiteHide

Formula:
Cu(HAsO4) · H2O
IMA Formula:
Cu2+(AsO3OH) · H2O

Crystallography of GeminiteHide

Crystal System:
Triclinic
Cell Parameters:
a = 6.63 Å, b = 8.11 Å, c = 15.73 Å
α = 92.01°, β = 93.87°, γ = 95.02°
Ratio:
a:b:c = 0.818 : 1 : 1.94
Unit Cell V:
839.91 ų (Calculated from Unit Cell)
Morphology:
Tabular {001}, slightly elongate [100].
Twinning:
Twinned polysynthetically parallel to {001}.

Type Occurrence of GeminiteHide

Place of Conservation of Type Material:
Museum d'Histoire Naturelle de Geneve, Geneva, Switzerland.
Associated Minerals at Type Locality:

Synonyms of GeminiteHide

Other Language Names for GeminiteHide

German:Geminit
Spanish:Geminita

Common AssociatesHide

Associated Minerals Based on Photo Data:
Yvonite22 photos of Geminite associated with Yvonite on mindat.org.
Pushcharovskite8 photos of Geminite associated with Pushcharovskite on mindat.org.
Bismuth7 photos of Geminite associated with Bismuth on mindat.org.
Quartz2 photos of Geminite associated with Quartz on mindat.org.
Rapidcreekite2 photos of Geminite associated with Rapidcreekite on mindat.org.
Arsenolite1 photo of Geminite associated with Arsenolite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

8.CB.05SerrabrancaiteMnPO4 · H2OMon. 2/m : B2/b
8.CB.10Hureaulite(Mn,Fe)5(PO4)2(HPO4)2 · 4H2OMon. 2/m : B2/b
8.CB.10SainfelditeCa5(AsO4)2(AsO3OH)2 · 4H2OMon. 2/m : B2/b
8.CB.10VillyaelleniteMnMn2Ca2(AsO4)2(HAsO4)2 · 4H2OMon. 2/m : B2/b
8.CB.10UM1997-09-AsO:CaHMgZn(Mg,Ca,Zn)5(AsO4)2(HAsO4)2 · 4H2OMon.
8.CB.10NyholmiteCd3Zn2(AsO4)2(HAsO4)2 · 4H2OMon. 2/m : B2/b
8.CB.10MiguelromeroiteMnMn2Mn2(AsO4)2(HAsO4)2 · 4H2OMon. 2/m : B2/b
8.CB.15FluckiteCaMn2+(HAsO4)2 · 2H2OTric. 1 : P1
8.CB.15KrautiteMn(HAsO4) · H2OMon. 2 : P21
8.CB.20Cobaltkoritnigite(Co,Zn)(HAsO4) · H2OTric. 1 : P1
8.CB.20KoritnigiteZn(HAsO4) · H2OTric. 1 : P1
8.CB.25YvoniteCu(HAsO4) · 2H2OTric.
8.CB.35SchubneliteFe3+VO4 · H2OTric.
8.CB.40RadovaniteCu2Fe3+(AsO4)(HAs3+O3)2 · H2OOrth. mmm (2/m 2/m 2/m) : Pnma
8.CB.45KazakhstaniteFe3+5V4+3V5+12O39(OH)9 · 9H2OMon.
8.CB.50KolovratiteNixZny(VO4)0.67(x+y) · nH2O
8.CB.55IrhtemiteCa4Mg(AsO4)2(HAsO4)2 · 4H2OMon.
8.CB.60BurgessiteCo2(H2O)4[AsO3(OH)]2(H2O)Mon. 2/m

Related Minerals - Hey's Chemical Index of Minerals GroupingHide

20.1.1LammeriteCu3(AsO4)2Mon.
20.1.2OliveniteCu2(AsO4)(OH)Mon. 2/m : P21/m
20.1.3ClinoclaseCu3(AsO4)(OH)3Mon. 2/m : P21/b
20.1.4CornwalliteCu5(AsO4)2(OH)4Mon. 2/m : P21/b
20.1.5CornubiteCu5(AsO4)2(OH)4Tric. 1 : P1
20.1.6Chlorotile (of Frenzel)
20.1.8EuchroiteCu2(AsO4)(OH) · 3H2OOrth. 2 2 2 : P21 21 21
20.1.9StrashimiriteCu8(AsO4)4(OH)4 · 5H2OMon.
20.1.10ArhbariteCu2Mg(AsO4)(OH)3Tric. 1 : P1
20.1.11LindackeriteCuCu4(AsO4)2(HAsO4)2 · 9H2OTric. 1 : P1
20.1.12ConichalciteCaCu(AsO4)(OH)Orth. 2 2 2 : P21 21 21
20.1.13LiroconiteCu2Al(AsO4)(OH)4 · 4H2OMon. 2/m
20.1.14CeruleiteCu2Al7(AsO4)4(OH)13 · 11.5H2OTric.
20.1.15ChenevixiteCu2Fe3+2(AsO4)2(OH)4Mon. 2/m : P21/m
20.1.16ArthuriteCuFe3+2(AsO4)2(OH)2 · 4H2OMon.

Fluorescence of GeminiteHide

Other InformationHide

Thermal Behaviour:
On heating, the mineral becomes anhydrous between 200°C and 250°C.
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 GeminiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Sarp, H., Perroud, P. (1990) La geminite, Cu2As2O7·3H2O, un nouveau minéral de la mine de Cap Garonne, Var, France. Schweizerische Mineralogische und Petrographische Mitteilungen: 70: 309-314.
Jambor, J.L. (1992) New mineral names. American Mineralogist: 77: 670-675.
Cooper, M.A., Hawthorne, F.C. (1995) The crystal structure of geminite, Cu2+(AsO3OH)(H2O), a heteropolyhedral sheet structure. The Canadian Mineralogist: 33: 1111-1118.
Prencipe, M., Pushcharovsky, D.Y., Sarp, H., Ferraris, G. (1996) Comparative crystal chemistry of geminite Cu[AsO3OH]H2O and related minerals. Moscow University Geology Bulletin: 51: 51-58.
Jambor, J.L., Pertsev, N.N., Roberts, A.C. (1996) New mineral names. American Mineralogist: 81: 766-770.
New Minerals (1997), New Minerals 1990-1994.
Jambor, J.L., Pertsev, N.N., Roberts, A.C. (1998) New mineral names. American Mineralogist: 83: 907-911.

Internet Links for GeminiteHide

Localities for GeminiteHide

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.
Czech Republic
 
  • Karlovy Vary Region
    • Krušné Hory Mts (Erzgebirge)
      • Jáchymov District (St Joachimsthal)
        • Jáchymov (St Joachimsthal)
Lapis 2002(7/8), 54
Lapis 2002(7/8), 54
France
 
  • Occitanie
    • Aude
      • Salsigne
[AmMin 84:197]
  • Provence-Alpes-Côte d'Azur
    • Var
      • Le Pradet
Schweiz.Min.Petr.Mitt.(1990) 70, 309-314
Germany
 
  • Saxony
    • Erzgebirge
      • Schlema-Hartenstein District
Lapis 1994(10), 36-39
Greece
 
  • Attikí Prefecture (Attica; Attika)
    • Lavrion District (Laurion; Laurium; Lavreotiki Municipality)
      • Lavrion District Mines
        • Agios Konstantinos [St Constantine] (Kamariza)
          • Kamariza Mines (Kamareza Mines)
            • Christiana Mine
Rieck, B., Kolitsch, U., Voudouris, P., Giester, G. and Tzeferis, P. (2018): Weitere Neufunde aus Lavrion, Griechenland. Mineralien-Welt 29 (5), 32-77 (in German).
Morocco
 
  • Drâa-Tafilalet Region
    • Ouarzazate Province
      • Tazenakht
        • Bou Azzer District (Bou Azer District)
          • Khder
Favreau, G. and Dietrich, J. E. (2006). Die Mineralien von Bou Azzer. Lapis 31(7/8), 27-68
Namibia
 
  • Oshikoto Region (Otjikoto Region)
    • Tsumeb
Hawthorne et al. (2011) Davidlloydite, ideally Zn3(AsO4)2(H2O)4, a new arsenate mineral from the Tsumeb mine, Otjikoto (Oshikoto) region, Namibia. Mineralogical Magazine 76(1): 45–57.
Poland
 
  • Lower Silesia (Dolnośląskie)
    • Legnica
      • Lubin District
Material analysed by University of Silesia
Mineral and/or Locality  
Mindat.org is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2018, except where stated. Mindat.org relies on the contributions of thousands of members and supporters.
Privacy Policy - Terms & Conditions - Contact Us Current server date and time: October 22, 2018 04:47:12 Page generated: October 10, 2018 04:37:04
Go to top of page