Chondrodite

chondrodite

antigorite

magnetite

iowaite

Images

Formula: Mg5(SiO4)2F2
Nesosilicate (insular SiO4 groups)
Specific gravity: 3.1 to 3.2
Hardness: 6 - 6½
Streak: White
Colour: Yellow, brown, red, rarely green
Solubility: Slightly soluble in hydrochloric acid
Common impurities: Ti,Al,Mn
Environments:

Carbonatites (rarely)
Metamorphic environments (typically)

Chondrodite occurs in contact or regionally metamorphosed dolomitic limestone or dolostone, associated with diopside, spinel and phlogopite.
It also may be found in serpentinite associated with magnetite, and in skarn associated with wollastonite, forsterite and monticellite.

Localities

The Ma On Shan Mine, Ma On Shan, Sha Tin District, New Territories, Hong Kong, China, is an abandoned iron mine, with both underground and open cast workings. The iron ores contain magnetite as the ore mineral and occur predominantly as masses of all sizes enclosed in a large skarn body formed by contact metasomatism of dolomitic limestone at the margins of a granite intrusion. In parts of the underground workings magnetite is also found in marble in contact with the granite. The skarn rocks consist mainly of tremolite, actinolite, diopside and garnet. Chondrodite occurs in veins and stringers associated with diopside and magnetite (Hong Kong Minerals (1991). Peng, C J. Hong Kong Urban Council)

At Palabora, Limpopo Province, South Africa, chondrodite occurs atypically in carbonatite, associated with calcite, magnetite, clinochlore and less commonly with iowaite (R&M.92.5.437).

Amity, Town of Warwick, Orange county, New York, USA, is an area of granite intrusions into marble and associated gneiss. The marble is mostly composed of white crystalline calcite that often has small flakes or spheres of graphite and phlogopite. Chondrodite is a common mineral, forming as agglomerations of dark brownish red crystals or crusty coatings on white marble; it is often associated with spinel (R&M 96.5.435).

At the Tilly Foster mine, Brewster, Putnam county, New York, USA, antigorite pseudomorphs after chondrodite have been found with magnetite on kaolinite (KL p233).

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