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Guimarãesite

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Djalma Guimarães
Formula:
Ca2Be4Zn5(PO4)6(OH)4 · 6H2O
Colour:
brown
Lustre:
Vitreous
Hardness:
Specific Gravity:
2.963 (Calculated)
Crystal System:
Monoclinic
Name:
Named in honor of Djalma Guimarães (5 November 1894, Santa Luzia, Minas Gerais, Brazil - 10 October 1973, Belo Horizonte, Minas Gerais, Brazil), mineralogist and geochemist, in recognition of his important contributions to Brazilian mineralogy and geology. He taught at Ouro the Preto Mining School and at the Federal University of Minas Gerais.
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Classification of GuimarãesiteHide

Approved
Approval Year:
2006
First Published:
2007
8.DA.10

8 : PHOSPHATES, ARSENATES, VANADATES
D : Phosphates, etc. with additional anions, with H2O
A : With small (and occasionally larger) cations

Physical Properties of GuimarãesiteHide

Vitreous
Transparency:
Transparent
Colour:
brown
Streak:
White
Hardness:
4½ on Mohs scale
Tenacity:
Brittle
Cleavage:
Perfect
perfect cleavage on {100} and good cleavage on {010} (by analogy)
Fracture:
Irregular/Uneven
Density:
2.963 g/cm3 (Calculated)

Optical Data of GuimarãesiteHide

Type:
Biaxial (-)
RI values:
nα = 1.596(2) nβ = 1.600(2) nγ = 1.602(2)
2V:
Measured: 55° to 75°, Calculated: 70°
Max Birefringence:
δ = 0.006
Image shows birefringence interference colour range (at 30µm thickness)
and does not take into account mineral colouration.
Surface Relief:
Moderate
Pleochroism:
Non-pleochroic

Chemical Properties of GuimarãesiteHide

Formula:
Ca2Be4Zn5(PO4)6(OH)4 · 6H2O
IMA Formula:
Ca2Zn5Be4(PO4)6(OH)4 · 6H2O

Crystallography of GuimarãesiteHide

Crystal System:
Monoclinic
Class (H-M):
2/m - Prismatic
Space Group:
B2/b
Setting:
C2/c
Cell Parameters:
a = 15.98(1) Å, b = 11.84(2) Å, c = 6.63(1) Å
β = 95.15(15)°
Ratio:
a:b:c = 1.35 : 1 : 0.56
Unit Cell V:
1,249.35 ų (Calculated from Unit Cell)
Z:
2

X-Ray Powder DiffractionHide

Powder Diffraction Data:
d-spacingIntensity
9.48 (90)
5.98 (100)
4.82 (80)
3.152 (90)
3.052 (70)
2.961 (70)
2.841 (70)
2.708 (80)

Type Occurrence of GuimarãesiteHide

General Appearance of Type Material:
peripheral zones (up to 0.1 mm thick) in crystals of roscherite-group minerals.
Place of Conservation of Type Material:
under the number DR591 in the Museu de Geociã ncias,
Instituto de Geociã ncias, Universidade de São Paulo, Rua do Lago, 562, 05508080, São Paulo, SP, Brazil.
Geological Setting of Type Material:
late fracture-filling mineral in a phosphate-rich granite pegmatite
Associated Minerals at Type Locality:
Reference:
Chukanov, N.V., Atencio, D., Zadov, A.E., Menezes, L.A.D., Coutinho, J.M.V. (2007) Guimarãesite, a new Zn-dominant monoclinic roscherite-group mineral from Itinga, Minas Gerais, Brazil. New Data on Minerals. Moscow: 42: 11-15.

Synonyms of GuimarãesiteHide

Other Language Names for GuimarãesiteHide

Relationship of Guimarãesite to other SpeciesHide

Other Members of this group:
AtencioiteCa2Fe2+3Mg2Be4(PO4)6(OH)4 · 6H2O
FootemineiteCa2Mn2+Mn2+2Mn2+2Be4(PO4)6(OH)4 · 6H2OTric. 1 : P1
GreifensteiniteCa2Fe2+5Be4(PO4)6(OH)4 · 6H2OMon.
OkruschiteCa2Mn2+5Be4(AsO4)6(OH)4·6H2OMon. 2/m : B2/b
RoscheriteCa2Mn2+5Be4(PO4)6(OH)4 · 6H2OMon. 2/m : B2/m
RuifrancoiteCa2(◻,Mn)2(Fe3+,Mn,Mg)4Be4(PO4)6(OH)4(OH,H2O)2 · 4H2OMon. 2/m : B2/b
ZanazziiteCa2Mg5Be4(PO4)6(OH)4 · 6H2OMon. 2/m : B2/b

Common AssociatesHide

Associated Minerals Based on Photo Data:
Quartz5 photos of Guimarãesite associated with Quartz on mindat.org.
Muscovite4 photos of Guimarãesite associated with Muscovite on mindat.org.
Eosphorite3 photos of Guimarãesite associated with Eosphorite on mindat.org.
Greifensteinite1 photo of Guimarãesite associated with Greifensteinite on mindat.org.
Zanazziite1 photo of Guimarãesite associated with Zanazziite on mindat.org.

Related Minerals - Nickel-Strunz GroupingHide

8.DA.05BearsiteBe2(AsO4)(OH) · 4H2OMon.
8.DA.05MoraesiteBe2(PO4)(OH) · 4H2OMon.
8.DA.10RoscheriteCa2Mn2+5Be4(PO4)6(OH)4 · 6H2OMon. 2/m : B2/m
8.DA.10ZanazziiteCa2Mg5Be4(PO4)6(OH)4 · 6H2OMon. 2/m : B2/b
8.DA.10GreifensteiniteCa2Fe2+5Be4(PO4)6(OH)4 · 6H2OMon.
8.DA.10AtencioiteCa2Fe2+3Mg2Be4(PO4)6(OH)4 · 6H2O
8.DA.10RuifrancoiteCa2(◻,Mn)2(Fe3+,Mn,Mg)4Be4(PO4)6(OH)4(OH,H2O)2 · 4H2OMon. 2/m : B2/b
8.DA.10FootemineiteCa2Mn2+Mn2+2Mn2+2Be4(PO4)6(OH)4 · 6H2OTric. 1 : P1
8.DA.15UraloliteCa2Be4(PO4)3(OH)3 · 5H2OMon.
8.DA.20WeinebeneiteCaBe3(PO4)2(OH)2 · 4H2OMon.
8.DA.25TiptopiteK2(Na,Ca)2Li3Be6(PO4)6(OH)2 · H2OHex.
8.DA.30Veszelyite(Cu,Zn)2Zn(PO4)2 · 2H2OMon. 2/m : P21/b
8.DA.35Kipushite(Cu,Zn)5Zn(PO4)2(OH)6 · H2OMon.
8.DA.35Philipsburgite(Cu,Zn)6(AsO4,PO4)2(OH)6 · H2OMon.
8.DA.40SpenceriteZn4(PO4)2(OH)2 · 3H2OMon. 2/m : P2/b
8.DA.45GlucineCaBe4(PO4)2(OH)4 · 0.5H2O
8.DA.50Ianbruceite[Zn2(OH)(H2O)(AsO4)](H2O)2Mon. 2/m : P21/b

Fluorescence of GuimarãesiteHide

Other InformationHide

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 GuimarãesiteHide

Reference List:
Sort by Year (asc) | by Year (desc) | by Author (A-Z) | by Author (Z-A)
Chukanov, N.V., Atencio, D., Zadov, A.E., Menezes, L.A.D., Coutinho, J.M.V. (2007) Guimarãesite, a new Zn-dominant monoclinic roscherite-group mineral from Itinga, Minas Gerais, Brazil. New Data on Minerals. Moscow: 42: 11-15.

Internet Links for GuimarãesiteHide

Localities for GuimarãesiteHide

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.
Brazil (TL)
 
  • Minas Gerais
    • Itinga
      • Taquaral
        • Piauí valley
IMA website
Luis Menezes
Mineral and/or Locality  
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