Annite
| Annite | ||
|---|---|---|
2V angle Calculated: 12° to 36° | | |
| Other characteristics | Diagnostic: occurrence: in magnesium poor igneous and metamorphic rocks. | |
| References | [7][8] | |
Annite is a
Annite was first described in 1868 for the first noted occurrence in
Properties
The relief of a mineral refers to the way a mineral may stand out in plane polarized light. A mineral may be referred to as having a low or high relief. Minerals with a high relief, such as annite, have sharp grain boundaries and display good fracture and cleavage. When viewed under a microscope, this mineral may appear to stick out of the other minerals in the thin section. Relief primarily depends on the index of refraction of the mineral.
Uses
Annite is a member of the mica group and has very similar properties as other micas such as muscovite and biotite. More importantly, annite is interesting to geologists because it can be used for potassium-argon dating. Because annite contains large amounts of potassium, it can be used to find the absolute age of articles older than 1000 years. This type of dating also preserves a record of the direction and intensity of the local magnetic field, giving field geologists better knowledge of their surroundings.[11]
References
- S2CID 235729616.
- ^ 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.
- ^ a b Kwak, 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
- ^ a b c Mindat.org
- ^ a b c d e f Handbook of Mineralogy
- 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
- ^ Eugster, H.P. and Wones, D.R.(1962) Stability relations of the ferruginous biotite, annite. 3, 82–125
