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Formula: Mg5(SiO4)2F2
Nesosilicate (insular SiO4 groups), humite subgroup,
humite group
Crystal System: Monoclinic
Specific gravity: 3.16 to 3.26 , 3.177 calculated
Hardness: 6 to 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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