Gedrite: Difference between revisions
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| caption = |
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| formula = (Mg;Fe<sup>2+</sup>)<sub>2</sub>[(Mg;Fe<sup>2+</sup>)<sub>3</sub>Al<sub>2</sub>](Si<sub>6</sub>Al<sub>2</sub>)O<sub>22</sub>(OH)<sub>2</sub> |
| formula = (Mg;Fe<sup>2+</sup>)<sub>2</sub>[(Mg;Fe<sup>2+</sup>)<sub>3</sub>Al<sub>2</sub>](Si<sub>6</sub>Al<sub>2</sub>)O<sub>22</sub>(OH)<sub>2</sub> |
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| symmetry = Orthorhombic 2/m 2/m 2/m |
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| molweight = |
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| unit cell = a = 18.59 Å, b = 17.89 Å, c = 5.3 Å; Z = 4 |
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| color = White, gray, brown, green |
| color = White, gray, brown, green |
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| habit = |
| habit = Bladed and prismatic crystals; fibrous and sheath like aggregates. |
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| system = [[Orthorhombic]] |
| system = [[Orthorhombic]] |
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| twinning = |
| twinning = |
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| cleavage = 56 and 126° - good; {210} perfect |
| cleavage = 56 and 126° - good; {210} perfect |
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| mohs = 5.5 - 6 |
| mohs = 5.5 - 6 |
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| luster = Vitreous to silky |
| luster = Vitreous to silky |
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| refractive = |
| refractive = n<sub>α</sub> = 1.671 n<sub>β</sub> = 1.681 n<sub>γ</sub> = 1.690 |
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| opticalprop = Biaxial (+) |
| opticalprop = Biaxial (+) |
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| birefringence = δ = 0.019 |
| birefringence = δ = 0.019 |
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| pleochroism = Weak to moderate |
| pleochroism = Weak to moderate |
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| 2V = Measured: 75° |
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| streak = |
| streak = |
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| gravity = 3.18 - 3.33 |
| gravity = 3.18 - 3.33 |
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| references = <ref name=Handbook>http://www.handbookofmineralogy.org/pdfs/gedrite.pdf Handbook of Mineralogy</ref><ref name=Webmin>http://webmineral.com/data/Gedrite.shtml Webmineral</ref><ref>http://www.mindat.org/min-1665.html Mindat</ref> |
| references = <ref name=Handbook>http://www.handbookofmineralogy.org/pdfs/gedrite.pdf Handbook of Mineralogy</ref><ref name=Webmin>http://webmineral.com/data/Gedrite.shtml Webmineral</ref><ref>http://www.mindat.org/min-1665.html Mindat</ref> |
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'''Gedrite''' is a [[silicate mineral]] of the [[amphibole]] group with formula: (Mg;Fe<sup>2+</sup>)<sub>2</sub>[(Mg;Fe<sup>2+</sup>)<sub>3</sub>Al<sub>2</sub>](Si<sub>6</sub>Al<sub>2</sub>)O<sub>22</sub>(OH)<sub>2</sub>. Gedrite occurs in [[Contact metamorphism|contact]] and medium to high grade [[metamorphic rock]]s in association with [[garnet]], [[cordierite]], [[anthophyllite]], [[cummingtonite]], [[sapphirine]], [[sillimanite]], [[kyanite]], [[quartz]], [[staurolite]] and [[biotite]].<ref name=Handbook/> |
'''Gedrite''' is a [[silicate mineral]] of the [[amphibole]] group with formula: (Mg;Fe<sup>2+</sup>)<sub>2</sub>[(Mg;Fe<sup>2+</sup>)<sub>3</sub>Al<sub>2</sub>](Si<sub>6</sub>Al<sub>2</sub>)O<sub>22</sub>(OH)<sub>2</sub>. |
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Gedrite occurs in [[Contact metamorphism|contact]] and medium to high grade [[metamorphic rock]]s in association with [[garnet]], [[cordierite]], [[anthophyllite]], [[cummingtonite]], [[sapphirine]], [[sillimanite]], [[kyanite]], [[quartz]], [[staurolite]] and [[biotite]].<ref name=Handbook/> |
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Gedrite was first described for an occurrence in Gedres, France in 1836.<ref name=Webmin/> |
Gedrite was first described for an occurrence in Gedres, France in 1836.<ref name=Webmin/> |
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Revision as of 00:53, 18 January 2011
| Gedrite | |
|---|---|
| General | |
| Category | Inosilicate |
| Formula (repeating unit) | (Mg;Fe2+)2[(Mg;Fe2+)3Al2](Si6Al2)O22(OH)2 |
| Crystal system | Orthorhombic |
| Space group | Orthorhombic 2/m 2/m 2/m |
| Unit cell | a = 18.59 Å, b = 17.89 Å, c = 5.3 Å; Z = 4 |
| Identification | |
| Color | White, gray, brown, green |
| Crystal habit | Bladed and prismatic crystals; fibrous and sheath like aggregates. |
| Cleavage | 56 and 126° - good; {210} perfect |
| Fracture | Splintery |
| Mohs scale hardness | 5.5 - 6 |
| Luster | Vitreous to silky |
| Diaphaneity | Translucent, will transmit light on thin edges. |
| Specific gravity | 3.18 - 3.33 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.671 nβ = 1.681 nγ = 1.690 |
| Birefringence | δ = 0.019 |
| Pleochroism | Weak to moderate |
| 2V angle | Measured: 75° |
| References | [1][2][3] |
Gedrite is a silicate mineral of the amphibole group with formula: (Mg;Fe2+)2[(Mg;Fe2+)3Al2](Si6Al2)O22(OH)2.
Gedrite occurs in contact and medium to high grade metamorphic rocks in association with garnet, cordierite, anthophyllite, cummingtonite, sapphirine, sillimanite, kyanite, quartz, staurolite and biotite.[1]
Gedrite was first described for an occurrence in Gedres, France in 1836.[2]
References
- ^ a b http://www.handbookofmineralogy.org/pdfs/gedrite.pdf Handbook of Mineralogy
- ^ a b http://webmineral.com/data/Gedrite.shtml Webmineral
- ^ http://www.mindat.org/min-1665.html Mindat
 | This article about a specific silicate mineral is a stub. You can help Wikipedia by expanding it. |