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Orthoclase from
Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar


Locality type:Area
Classification
Species:Orthoclase
Formula:K(AlSi3O8)
Comments:Gemmy facetable crystals In elder litterature called "orthoclase". All are Sanidine. X-ray studies of a bright yellow to colorless feldspar collected in 2001 at one of the localities around Itrongay and other samples showed it to be high to low sanidine, not orthoclase (Simmons and Falster 2002). Further investigations by Ackermann et al. (2005) on the cation distribution and ordering of Si, Al, Fe on the tetragonal (T1) site of a K-feldspar from Itrongay, showed it to be a monoclinic low sanidine (for more details see the paper at http://www.escholarship.org/uc/item/20f968sx ).
Habit:prismatic
Colour:Yellow
Confirmation
Validity:Erroneously Reported
Data
Mineral Data:Click here to view Orthoclase data
Locality Data:Click here to view Itrongay (Itrongahy), Mahasoa Est, Betroka District, Anosy, Madagascar
Data Identifiers
Mindat Occurrence Record ID:79780
Long-form Identifier:1:3:79780:5
GUID (UUID V4):0
References
www.mindat.org (n.d.) http://www.mindat.org/mesg-7-219075.html
Ungemach, Henri (1916) Contribution à la Minéralogie de Madagascar. Bulletin de Minéralogie, 39 (1) 5-38 doi:10.3406/bulmi.1916.3635
Mason, Anita (1976) The World of Rocks and Minerals. Larousse & Co., Inc., New York.
Pezzotta, Federico (2001) Madagascar. extraLapis English 1. Lapis International LLCp.30
 
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