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| imagesize =
| imagesize =
| caption =
| caption =
| formula = Ca<sub>5</sub>[(HAsO<sub>4</sub>)<sub>2</sub><nowiki>|</nowiki>(AsO<sub>4</sub>)2]·5(H<sub>2</sub>O)
| formula = Ca<sub>5</sub>(HAsO<sub>4</sub>)<sub>2</sub>(AsO<sub>4</sub>)<sub>2</sub>·5(H<sub>2</sub>O)
| strunz = 08.CJ.25
| strunz = 08.CJ.25
| symmetry = Monoclinic prismatic<br/>[[H-M symbol]]: (2/m) <br/>[[Space group]]: P 2<sub>1</sub>/c
| symmetry = monoclinic
| unit cell = V 1,332.98 ų
| unit cell = a = 5.81 Å, b = 10.19 Å, c = 22.7 Å; β = 97.32°; Z=3
| molweight =848.16 g
| molweight = 848.16 g
| color = pale rose, colorless, white
| color = Pale rose, colorless, white
| habit = As acicular/bladed crystals occurring in cross-fiber veinlets; spherulitic
⚫
| habit = radial
| system = monoclinic
| system = [[Monoclinic]]
| twinning = penetration
| twinning = Penetration
| cleavage = good
| cleavage = Good one plane
| fracture = fibrous
| fracture =
| tenacity =brittle
| tenacity = Brittle
| mohs = 3.5
| mohs = 3.5
| luster = vitreous(glassy)
| luster = Sub-vitreous, silky, pearly
| refractive = n<sub>α</sub> = 1.650 - 1.651 n<sub>β</sub> = 1.654 - 1.656 n<sub>γ</sub> = 1.656 - 1.661
| refractive = 1.65-1.66
| opticalprop = biaxial
| opticalprop = Biaxial (-)
| birefringence = δ = 0.011
| birefringence = δ = 0.006 - 0.010
| pleochroism = trichroic
| pleochroism = Non-pleochroic
| 2V = Measured: 70°
| streak = white
⚫
| streak = White
| gravity = 3.17
| gravity = 3.17
| density =
| density =
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| diagnostic =
| diagnostic =
| solubility =
| solubility =
| diaphaneity = transparent
| diaphaneity = Transparent
| other =
| other =
| references = <ref name=HBM>[http://rruff.geo.arizona.edu/doclib/hom/vladimirite.pdf Handbook of Mineralogy]</ref><ref>Catti, and M., Ivaldi, G.(1981) Mechanism of the Reaction Ferrasite (Dimorph of Vladimirite) and Structure of the Latter Phase, B 157, 119-130</ref><ref name=Mindat>[http://www.mindat.org/min-4195.html Mindat.org]</ref><ref>[http://webmineral.com/data/Vladimirite.shtml Webmineral]</ref>
| references =
<ref>Catti, and M., Ivaldi, G.(1981) Mechanism of the Reaction Ferrasite (Dimorph of Vladimirite) and Structure of the Latter Phase, B 157, 119-130</ref>
<ref>^Roberts, W.C., Campbell, T.J., and Rapp Jr., G.R.
(1990) Encyclopedia of minerals(2nd edition).294p. Library of Congress Cataloging, Washington, D.C.</ref>
<ref>http://euromin.w3sites.net/mineraux/VLADIMIRITE.html</ref>
<ref>http://www.mindat.org/min-4195.html</ref>
<ref>http://www.minsocam.org/ammin/AM40/AM40_551.pdf</ref>
<ref>http://webmineral.com/specimens/picshow.php?id=2552&target=Vladimirite</ref>
<ref>http://webmineral.com/data/Vladimirite.shtml></ref>
}}
}}
'''Vladimirite''' has a general [[chemical formula]] of Ca<sub>5</sub> [(HAsO<sub>4</sub>)<sub>2</sub>|(AsO<sub>4</sub>)2]·5H<sub>2</sub>O. It is named after the Vladimirovskoye [[Deposition (geology)|deposit]] in [[Russia]], where it was discovered in the 1950s. Vladimirite is a secondary mineral in the oxidized zone of arsenic-bearing mineral deposits.
'''Vladimirite''' is a rare [[calcium]] [[arsenate mineral]] with a [[chemical formula|formula]] of Ca<sub>5</sub>(HAsO<sub>4</sub>)<sub>2</sub>(AsO<sub>4</sub>)<sub>2</sub>·5H<sub>2</sub>O. It is named after the Vladimirovskoye [[Deposition (geology)|deposit]] in [[Russia]], where it was discovered in the 1950s.


Vladimirite is monoclinic-prismatic, which means crystallographically, it contains three axes of unequal length and the angles between two of the axes are 90 degrees, and one is less than 90 degrees. It belongs to the space group P2<sub>1</sub>/c. The mineral also has an orthorhombic polytype. In terms of its optical properties, Vladimirite is anisotropic which means the velocity of light varies depending on direction through the mineral. Relief is a diagnostic characteristic of a mineral in plane polarized light that refers to the various ways different minerals "stand out". Vladimirite's calculated relief is 1.65-1.661, which is moderate. It is colorless in plane polarized light, and it is weakly pleochroic. Pleochroism is the variety of colors under plane polarized light displayed by crystals at various angles.
Vladimirite is [[monoclinic]]-prismatic, which means crystallographically, it contains three axes of unequal length and the angles between two of the axes are 90 degrees, and one is less than 90 degrees. It belongs to the space group P2<sub>1</sub>/c. The mineral also has an orthorhombic [[Polymorphism (materials science}|polytype]]. In terms of its optical properties, vladimirite is anisotropic which means the velocity of light varies depending on direction through the mineral. Relief is a diagnostic characteristic of a mineral in plane polarized light that refers to the various ways different minerals "stand out". Vladimirite's calculated relief is 1.65-1.661, which is moderate. It is colorless in plane polarized light, and it is weakly pleochroic. Pleochroism is the variety of colors under plane polarized light displayed by crystals at various angles.


==Occurrence==
Importance:
Vladimirite was first described in 1953 at two deposits in Russia, the Khovu-Aksy nickel-cobalt deposit, [[Tuva Republic]], and the Vladimirovskoye cobalt deposit, [[Altai Mountains]], [[Altaiskii Krai]], Siberia.<ref name=Mindat/>
Vladimirite has not yet been structurally studied. However, [[ferrasite]], a polymorph of vladimirite, has been the subject of several structural and crystal-chemical scientific studies. Ferrasite has peculiar and very complicated dehydration behaviour. Ferrasite dehydrates very slowly in dry air at room temperature.
It is a secondary mineral in the [[Redox|oxidized]] zone of arsenic-bearing [[ore]] deposits. It occurs with [[picropharmacolite]], [[erythrite]] and [[aragonite]]. It has been reported from the [[Richelsdorf Mountains]], [[Hesse]], [[Germany]]; the Bou Azzer district, [[Morocco]] and the Mohawk mine, [[Keweenaw County, Michigan]].<ref name=HBM/>


== References ==
== References ==
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[[Category:Calcium minerals]]
[[Category:Calcium minerals]]
[[Category:Arsenate minerals]]
[[Category:Arsenate minerals]]
[[Category:Monoclinic minerals]]
{{mineral-stub}}
{{mineral-stub}}

Revision as of 16:58, 21 February 2012

Vladimirite
General
CategoryArsenate minerals
Formula
(repeating unit)		Ca5(HAsO4)2(AsO4)2·5(H2O)
Strunz classification08.CJ.25
Crystal systemMonoclinic
Space groupMonoclinic prismatic
H-M symbol: (2/m)
Space group: P 21/c
Unit cella = 5.81 Å, b = 10.19 Å, c = 22.7 Å; β = 97.32°; Z=3
Identification
Formula mass848.16 g
ColorPale rose, colorless, white
Crystal habitAs acicular/bladed crystals occurring in cross-fiber veinlets; spherulitic
TwinningPenetration
CleavageGood one plane
TenacityBrittle
Mohs scale hardness3.5
LusterSub-vitreous, silky, pearly
StreakWhite
DiaphaneityTransparent
Specific gravity3.17
Optical propertiesBiaxial (-)
Refractive indexnα = 1.650 - 1.651 nβ = 1.654 - 1.656 nγ = 1.656 - 1.661
Birefringenceδ = 0.006 - 0.010
PleochroismNon-pleochroic
2V angleMeasured: 70°
References[1][2][3][4]

Vladimirite is a rare calcium arsenate mineral with a formula of Ca5(HAsO4)2(AsO4)2·5H2O. It is named after the Vladimirovskoye deposit in Russia, where it was discovered in the 1950s.

Vladimirite is monoclinic-prismatic, which means crystallographically, it contains three axes of unequal length and the angles between two of the axes are 90 degrees, and one is less than 90 degrees. It belongs to the space group P21/c. The mineral also has an orthorhombic [[Polymorphism (materials science}|polytype]]. In terms of its optical properties, vladimirite is anisotropic which means the velocity of light varies depending on direction through the mineral. Relief is a diagnostic characteristic of a mineral in plane polarized light that refers to the various ways different minerals "stand out". Vladimirite's calculated relief is 1.65-1.661, which is moderate. It is colorless in plane polarized light, and it is weakly pleochroic. Pleochroism is the variety of colors under plane polarized light displayed by crystals at various angles.

Occurrence

Vladimirite was first described in 1953 at two deposits in Russia, the Khovu-Aksy nickel-cobalt deposit, Tuva Republic, and the Vladimirovskoye cobalt deposit, Altai Mountains, Altaiskii Krai, Siberia.[3] It is a secondary mineral in the oxidized zone of arsenic-bearing ore deposits. It occurs with picropharmacolite, erythrite and aragonite. It has been reported from the Richelsdorf Mountains, Hesse, Germany; the Bou Azzer district, Morocco and the Mohawk mine, Keweenaw County, Michigan.[1]

References

  1. ^ a b Handbook of Mineralogy
  2. ^ Catti, and M., Ivaldi, G.(1981) Mechanism of the Reaction Ferrasite (Dimorph of Vladimirite) and Structure of the Latter Phase, B 157, 119-130
  3. ^ a b Mindat.org
  4. ^ Webmineral
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