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| {{Infobox mineral | {{Infobox mineral | ||
| |name = Annite | |name = Annite | ||
| |category = ] mica group | |||
| |category = mica group, biotite-phlogopite series. The hydroxyll analogue of Flourannite. | |||
| |formula = KFe<sub>3</sub><sup>2+</sup></sup> |
|formula = KFe<sub>3</sub><sup>2+</sup></sup>AlSi<sub>3</sub>O<sub>10</sub>(OH,F)<sub>2</sub> | ||
| | symmetry = Monoclinic 2/m | |||
| | unit cell = a = 5.39 Å, b = 9.33 Å, c = 10.29 Å; β = 100°; Z = 2 | |||
| |molecular weight = 512.88 g | |molecular weight = 512.88 g | ||
| |color = |
|color = Brown to black | ||
| |habit = usually in "blocks" of thin sheets or as aggregations of foliated thin scales. Includes large, well formed pseudohexagonal prisms up to 12 cm across and 15 cm long.<ref>Hazen, R.M. and C.W. Burnham (1973) The crystal structures | |habit = usually in "blocks" of thin sheets or as aggregations of foliated thin scales. Includes large, well formed pseudohexagonal prisms up to 12 cm across and 15 cm long.<ref>Hazen, R.M. and C.W. Burnham (1973) The crystal structures | ||
| of one-layer phlogopite and annite. Amer. Mineral., 58, 889{900.</ref> | of one-layer phlogopite and annite. Amer. Mineral., 58, 889{900.</ref> | ||
| |system = |
|system = ], pseudohexagonal | ||
| |twinning = contact twins with composition surface on {001} and twin axis {310} | |twinning = contact twins with composition surface on {001} and twin axis {310} | ||
| |cleavage = perfect in one direction {001}<ref>Deer, W.A., R.A. Howie, and J. Zussman (1963) Rock-forming minerals, v. 3, sheet silicates, | |cleavage = perfect in one direction {001}<ref>Deer, W.A., R.A. Howie, and J. Zussman (1963) Rock-forming minerals, v. 3, sheet silicates, 55{84}.</ref> | ||
| 55{84}.</ref> | |||
| |fracture = uneven | |fracture = uneven | ||
| |tenacity = flexible<ref>Eugster, H.P. and D.R. Wones (1962) Stability relations of the ferruginous biotite, | |tenacity = flexible<ref>Eugster, H.P. and D.R. Wones (1962) Stability relations of the ferruginous biotite, annite. J. Petrol., 3, 82{125.</ref> | ||
| annite. J. Petrol., 3, 82{125.</ref> | |||
| |mohs = 2.5 - 3 | |mohs = 2.5 - 3 | ||
| |luster = submetallic to vitreous; pearly on cleavage surfaces<ref>Dana, E.S. (1892) Dana's system of mineralogy, (6th edition), 634.</ref> | |luster = submetallic to vitreous; pearly on cleavage surfaces<ref>Dana, E.S. (1892) Dana's system of mineralogy, (6th edition), 634.</ref> | ||
| | opticalprop = Biaxial (-) | |||
| |optical properties = translucent to transparent<ref>Kwak, T.A.P. and P.W. | |||
| | refractive = n<sub>α</sub> = 1.625 - 1.631 n<sub>β</sub> = 1.690 n<sub>γ</sub> = 1.691 - 1.697 | |||
| ⚫ | Askins (1981) Geology and genesis of the F-Sn-W(-Be-Zn) skarn (wrigglite) at Moina, Tasmania. | ||
| | pleochroism = X = brown; Y = Z = dark brown | |||
| Econ. Geol., 76, 439{467).</ref> | |||
| | 2V = Calculated: 12° to 36° | |||
| |streak = brownish white | |streak = brownish white | ||
| |gravity = approximately 3.3 |
|gravity = approximately 3.3 | ||
| |density = |
|density = | ||
| ⚫ | | diaphaniety = translucent to transparent<ref>Kwak, T.A.P. and P.W. Askins (1981) Geology and genesis of the F-Sn-W(-Be-Zn) skarn (wrigglite) at Moina, Tasmania. Econ. Geol., 76, 439{467).</ref> | ||
| |other = diagnostic: |
|other = diagnostic: occurrence: in magnesium poor igneous and metamorphic rocks. | ||
| | references = <ref name=Mindat></ref><ref name=HBM></ref> | |||
| }} | }} | ||
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| '''Annite''' is a ] mineral in the ] family. It has a chemical formula of KFe<sub>3</sub><sup>2+</sup></sup>AlSi<sub>3</sub>O<sub>10</sub>]. | |||
| ⚫ | |||
| ⚫ | '''Annite''' is a ] mineral in the ] family. It has a chemical formula of KFe<sub>3</sub><sup>2+</sup></sup>AlSi<sub>3</sub>O<sub>10</sub>(OH,F)<sub>2</sub>.<ref name=HBM/> Annite is the ] end member of the ] mica group, the iron rich analogue of ] rich ].<ref>Deer, W. A., R. A. Howie and J. Zussman, ''An Introduction to the Rock Forming Minerals,'' Longman, 1966, p. 212 ISBN 0582442109</ref> | ||
| ⚫ | Annite was first described in 1868 for the first noted occurrence in ], ], ], USA |
||
| ⚫ | Annite was first described in 1868 for the first noted occurrence in ], ], ], USA.<ref name=Mindat/> It also occurs on ], ].<ref name=HBM/> It occurs in ] and ] that are deficient in magnesium. It occurs associated with ] and ] in the ].<ref name=HBM/> | ||
| ==References== | ==References== | ||
Revision as of 14:15, 29 September 2010
| Annite | |
|---|---|
| General | |
| Category | Silicate mineral mica group |
| Formula (repeating unit) | KFe3AlSi3O10(OH,F)2 |
| Crystal system | Monoclinic, pseudohexagonal |
| Space group | Monoclinic 2/m |
| Unit cell | a = 5.39 Å, b = 9.33 Å, c = 10.29 Å; β = 100°; Z = 2 |
| Identification | |
| Color | Brown to black |
| Crystal habit | usually in "blocks" of thin sheets or as aggregations of foliated thin scales. Includes large, well formed pseudohexagonal prisms up to 12 cm across and 15 cm long. |
| Twinning | contact twins with composition surface on {001} and twin axis {310} |
| Cleavage | perfect in one direction {001} |
| Fracture | uneven |
| Tenacity | flexible |
| Mohs scale hardness | 2.5 - 3 |
| Luster | submetallic to vitreous; pearly on cleavage surfaces |
| Streak | brownish white |
| Specific gravity | approximately 3.3 |
| Optical properties | Biaxial (-) |
| Refractive index | nα = 1.625 - 1.631 nβ = 1.690 nγ = 1.691 - 1.697 |
| Pleochroism | X = brown; Y = Z = dark brown |
| 2V angle | Calculated: 12° to 36° |
| Other characteristics | diagnostic: occurrence: in magnesium poor igneous and metamorphic rocks. |
| References | |
Annite is a phyllosilicate mineral in the mica family. It has a chemical formula of KFe3AlSi3O10(OH,F)2. Annite is the iron end member of the biotite mica group, the iron rich analogue of magnesium rich phlogopite.
Annite was first described in 1868 for the first noted occurrence in Cape Ann, Rockport, Essex County, Massachusetts, USA. It also occurs on Pikes Peak, El Paso County, Colorado. It occurs in igneous and metamorphic rocks that are deficient in magnesium. It occurs associated with fluorite and zircon in the type locality.
References
- Hazen, R.M. and C.W. Burnham (1973) The crystal structures of one-layer phlogopite and annite. Amer. Mineral., 58, 889{900.
- Deer, W.A., R.A. Howie, and J. Zussman (1963) Rock-forming minerals, v. 3, sheet silicates, 55{84}.
- Eugster, H.P. and D.R. Wones (1962) Stability relations of the ferruginous biotite, annite. J. Petrol., 3, 82{125.
- Dana, E.S. (1892) Dana's system of mineralogy, (6th edition), 634.
- ^ Mindat.org
- ^ Handbook of Mineralogy
- Kwak, T.A.P. and P.W. Askins (1981) Geology and genesis of the F-Sn-W(-Be-Zn) skarn (wrigglite) at Moina, Tasmania. Econ. Geol., 76, 439{467).
- Deer, W. A., R. A. Howie and J. Zussman, An Introduction to the Rock Forming Minerals, Longman, 1966, p. 212 ISBN 0582442109
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