Mineral description : Margarite

Margarite as a thin rim around a corundum crystal in andesine. The rock comes from an anorthosite. From Södra yxesjön, Värmland.

Mineral class	Silicates : Mica group
Chemical formula	CaAl2(Al2Si2)O10(OH)2
Crystal system	Monoclinic
Habitus	Foliated micaceous aggregates with up to 3 cm sheets or massive. Rarely as thin pseudohexagonal tabular crystals.
Cleavage	Perfect {001}, sheets brittle fracture.
Hardness	3.5 - 4.5
Density	2.99-3.08
Color	Grayish, pale pink, yellow to green.
Streak	White
Luster	Vitreous, pearly on cleavage, translucent.
Description
Occurance	In low and medium-grade metamorphic rocks. In chlorite and mica schists.
Associates	Corundum, diaspore, tourmaline, staurolite, glaucophane, chlorite, magnetite, spinel, andalusite, calcite, quartz.
Notes	Sometimes formed as an alteration product of corundum.htm.
Localities	A not so common mineral in Scandinavia. Sweden : Some localities known Tvärå, Torsby, Värmland. Västra Frölunda, Göteborg, Bohuslän. Södra Yxesjön, Eda, Värmland. Norway : Some localities known Kongsfjell area, Bleikvatnet, South of Mo i Rana. In contact zone between clinozoisite and corundum. Duestöl and Almklovseter, Sunnmöre. As bands in eklogites. Seljenes, Nordpoll, Selje. As up to 5 cm nodules in a labradorite. Duestöl, Bergen-field. Light red margarite in muscovite aggregates in a metamorphosed anorthosite. Selje / Almklovdal area. As a major constituent of metamorphosed anothosites. South Kalskaret, Tafjord. Small amounts of margarite in corundum nodules in an anorthosite layer. Finland : At least one locality Juurakko pegmatite, Orivesi, Southern Finland. Pseudomorphs after topaz.

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