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Gemstones 250x250

The Mineral clinohumite

Clinohumite with Spinel

Clinohumite is a member of the humite group, and is chemically similar to Humite, with a very slightly modified chemical formula and different crystal form. Though Clinohumite is not a common mineral, it occurs more frequently and in better examples than its namesake Humite.

Chemical Formula

(Mg,Fe2+)9(SiO4)4(F,OH)2

Color

Dark red, reddish-brown, brown, yellowish-brown, yellow

Crystal System

Monoclinic

Properties

Streak
White
Hardness
6
Transparency
Transparent to translucent
Specific Gravity
3.2 - 3.4
Luster
Resinous, vitreous
Cleavage
3,1
Fracture
Subconchoidal to uneven
Tenacity
Brittle
Other ID Marks
May fluoresce yellow to orange in shortwave ultraviolet light.

Crystal Habits

Crystals may be tabular and prismatic, usually as complex crystals with rounded faces. Crystals may also be twinned in a vertical plane. Most frequently in grainy and crude masses.

3D Crystal Atlas

Additional Information

Composition
Magnesium iron fluoro-hydroxyl-silicate
In Group
Silicates; Nesosilicates; Humite Group
Striking Features
Color, crystal habits, and mode of occurrence
Environment
In marble deposits of metamorphosed limestones and dolomites.
Rock Type
Metamorphic

Varieties

 -   Form of Clinohumite lacking fluorine it its chemical structure, containing only hydroxyl at the end of its chemical formula. Hydroxylclinohumite is also deficient in iron, which is usually present in Clinohumite. Hydroxylclinohumite was classified in 1998 and is considered an individual mineral by the IMA.

Uses

Clinohumite is of interest to collectors, especially the rare transparent forms which are highly collectible. Gems for collectors are ocassionally cut from transparent stones.

Noteworthy Localities

The best formation of Clinohumite, in the form of outstanding orange crystals with good transparency, is from Kukh-i-Lal, Pamir Mts, Tajikistan. Sharp crystals and grains of Hydroxylclinohumite of excellent quality come from Sar-e-Sang, Kokcha Valley, Badakhshan Province, Afghanistan. Clinohumite associated with contrasting dark Spinel is found in the Hunza Valley, Gilgit, Pakistan.

Gemmy microcrystals have been found at Monte Somma, Vesuvius, Italy; and orange crystal grains from the Málaga region, Andalusia, Spain. In the U.S., large crystal clusters, almost always associated with Spinel, were found at the Rudy farm locality, Edenville, Orange Co., New York.

Common Mineral Associations

Calcite, Spinel, Phlogopite, Diopside

clinohumite Photos



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