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Chondrodite is the most prevalent and well-known member of the humite group. It is named for the Greek term "chondros", meaning grainy, alluding to the frequent grainy habit of this mineral.
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Chemical Formula |
(Mg,Fe2+)2(SiO4)2(F,OH)2 |
Composition |
Magnesium iron fluoro-hydroxyl-silicate |
Color |
Brown, reddish-brown, yellowish-brown, mustard-yellow, pale yellow, yellowish-gray, greenish-brown, orange |
Streak |
White |
Hardness |
6 - 6.5 |
Crystal System |
Monoclinic |
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Crystal Forms and Aggregates |
Crystals are usually complex, with faces in an oval "saucer" form. Less commonly tabular, and rarely prismatic. Often in grainy and crude masses. |
Transparency |
Transparent to nearly opaque |
Specific Gravity |
3.1 - 3.2 |
Luster |
Resinous, vitreous |
Cleavage |
3,1 |
Fracture |
Subconchoidal to uneven |
Tenacity |
Brittle |
Other ID Marks |
May display yellow fluorescence. |
In Group |
Silicates; Nesosilicates; Humite Group |
Striking Features |
Mode of occurrence, hardness, low density |
Environment |
In marbles, metamorphosed dolomites and hornfels, serpentine deposits, and altered volcanic rock. |
Rock Type |
Metamorphic |
Popularity (1-4)
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3 |
Prevalence (1-3)
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2 |
Demand (1-3) |
2 |
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Good examples of this mineral from classic localities are highly desirable to collectors.
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Though Chondrodite is the most common member of the Humite Group, it is only found in collectible specimens in few localities throughout the world. Bright orange-yellow Chondrodite comes from the marbles of Mogok, Burma (Myanmar); and brown Chondrodite from the Sar-e-Sang area in the Koksha Valley, Badakhshan Province, Afghanistan.
Brightly colored, small crystals have come from Kaveltorp Mine, Kopparberg, Västmanland, Sweden; and the the type locality for this mineral is Pargas, Finland. Transparent Chondrodite microcrystals were found in the San Vito Quarry, Monte Somma, Vesuvius, Italy. Reddish-brown, transparent Chondrodite comes from the Palabora mine, Phalaborwa, Limpopo Province, South Africa.
In the U.S., the most famous and classic locality for Chondrodite is the long-closed Tilly Foster Mine in Brewster, Putnam Co., New York. This location has produced the best crystals of this mineral. Large crystals and grainy groups have come from several places in the Franklin marble, including Amity, Orange Co., New York; and across the state line at Franklin, Ogdensberg, Sparta, and Newton, all in Sussex Co., New Jersey.
In Canada, small crystals in marble come from the Cardiff Mine, Haliburton Co., Ontario.
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Garnets - Generally harder, crystals less complex.Zircon - Harder and different crystal shapes.
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