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.[2]
Twinning
Contact twins with composition surface on {001} and twin axis {310}
Cleavage
Perfect in one direction {001}[3]
Fracture
Uneven
Tenacity
Flexible[4]
Mohs scale hardness
2.5–3
Luster
Submetallic to vitreous; pearly on cleavage surfaces[5]
Streak
Brownish white
Diaphaneity
Translucent to transparent[6]
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
[7][8]
Annite is a phyllosilicate mineral in the mica family. It has a chemical formula of KFe32+AlSi3O10(OH)2.[8] Annite is the iron end member of the biotite mica group, the iron rich analogue of magnesium rich phlogopite.[9] Annite is monoclinic and contains tabular crystals and cleavage fragments with pseudohexagonal outlines.[6] There are contact twins with composition surface {001} and twin axis {310}.[10]
Annite was first described in 1868 for the first noted occurrence in Cape Ann, Rockport, Essex County, Massachusetts, US.[7] It also occurs on Pikes Peak, El Paso County, Colorado.[8] It occurs in igneous and metamorphic rocks that are deficient in magnesium and is associated with fluorite and zircon in the type locality.[8]
^Hazen, R.M. and Burnham, C.W. (1973) The crystal structures
of one-layer phlogopite and annite. American Mineralogist, 58, 889–900.
^Deer, W.A., Howie, R.A., and Zussman, J. (1963) Sheet Silicates. Rock-forming minerals Volume 3, 55–84.
^Eugster, H.P. and Wones, D.R. (1962) Annite. Stability relations of the ferruginous biotite. 3, 82–125
^Dana, E.S. (1892) Dana's system of mineralogy, (6th edition), 634.
^ abKwak, T.A.P. and Askins, P.W. (1981) Geology and genesis of the F-Sn-W(-Be-Zn) skarn (wrigglite) at Moina, Tasmania. Economical Geology, 76, 439–467
^ abMindat.org
^ abcdHandbook of Mineralogy
^Deer, W. A., R. A. Howie and Zussman, J., An Introduction to the Rock Forming Minerals, Longman, 1966, p. 212 ISBN 0-582-44210-9
^Anthony,J.W., Bideaux, R.A., Bladh, K.W., and Nichols, C.M. (1995), Handbook of Mineralogy, Volume II, Silica, Silicates Part 1, p. 31
Annite is a phyllosilicate mineral in the mica family. It has a chemical formula of KFe32+AlSi3O10(OH)2. Annite is the iron end member of the biotite...
OH)2. It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more aluminous end-members include...
represented by variable amounts of the endmembers phlogopite, siderophyllite, annite, and eastonite. In contrast, a mineral group is a grouping of mineral species...
are found in Trenton Quarry. The minerals found are albite, almandine, annite, beryl, aquamarine, biotite, columbite, elbaite, microcline, muscovite,...
contain rare idiomorphic amphibole (Fe-hornblende and Fe-edenite), biotite (annite 25%-35%), plagioclase (An3), along with K-feldspar and quartz. (Mafti, 2001)...
aluminium. However less Al-rich phyllosilicates may be included, such as annite. Other common accessory minerals are apatite, titanite, zircon and other...
and amphibole are characteristics of typical alkaline rocks. Biotite is annite, with high Fe/Mg ratio. The accessory minerals are magnetite, ilmenite,...
Apg Annabergite Anb Arsenquatrandorite Aado Abelsonite Abl Allantoin Aan Annite Ann Arsentsumebite Atsu Abenakiite-(Ce) Abk-Ce Allargentum All Anorpiment...
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