Clinohumite

minerals

forsterite

ludwigite

titanium

Images

Formula: Mg9(SiO4)4F2
Nesosilicate (insular SiO4 groups)
Specific gravity: 3.17 to 3.35
Hardness: 6
Streak: White
Colour: Brown, yellow, white, orange, reddish brown.
Common impurities: Fe,Ti,Al,Mn,Ca,(OH)
Environments:

Carbonatites
Metamorphic environments

Clinohumite may be found in dolostone, kimberlite, limestone and peridotite. Titanium is a minor constituent of clinohumite in most occurrences. Clinohumite is stable throughout the upper mantle to depths of at least 410 km.
It occurs in contact metamorphic zones in dolostone and metasomatised limestone adjacent to felsic plutonic rocks, in serpentine and talc schist, and also in carbonatites. Associated minerals include grossular, wollastonite, forsterite, monticellite, cuspidine, fluoborite, ludwigite, dolomite, calcite, talc, biotite, spinel, vesuvianite, sanidine, meionite and nepheline (HOM).

Localities

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. Clinohumite occurs as crude brownish yellow crystals in the marble, almost always associated with spinel (R&M 96.5.435-436).

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