Chondrodite
Chondrodite is a known member of the Humite Group of minerals which includes Chondrodite, Clinohumite, Humite and Norbergite. Faceted Chondrodite is fairly rare. Faceted gems are beautiful in colours of light yellowish, yellow, deep and brown-red to deep orangish red. Some Chondrodite gems may display fluorescence of orangish-yellow under shortwave (SW) UV light and orange under longwave (LW) UV light. You will definitely understand Chondrodite gem exhibiting fluorescence under UV light if you hover your cursor over the picture above.
Chondrodite was known as in 1817 by Swedish historian Baron Abraham Constantin Mouradgea d’Ohsson (1779-1851) through the Greek word Χόνδρος (chondros) meaning grain in allusion to its habit of occurring in separated grains. d’Ohsson called Chondrodite “a stone that is yellow Pargas”.
There are several sources of Chondrodite round the world, but only a product that is few crystals. One supply of small gemmy crystals is the Tilly Foster Mine in Brewster, New York. Other sources are Badakhshan (Badakshan; Badahsan) Province, Afghanistan; Palabora mine, Loolekop, Phalaborwa, Limpopo Province, South Africa; and Mogok, Sagaing District, Mandalay Division, Myanmar (Burma).
Distribution: from Pargas, Hangelby, and Sibbo, Finland. At Kafveltorp, near Kopparberg, Sweden. From Monte Somma and Vesuvius, Campania, Italy. At Le Chipal, Vosges, France. From Bhandara, Maharashtra, India. In America, fine crystals through the Tilly Foster mine, Brewster, Putnam County, and Amity, Orange County, brand new York; at Franklin and Sparta, Sussex County, New Jersey; Johnson Camp, Cochise County, and the Lakeshore mine, Pinal County, Arizona; and Crestmore, Riverside County, California. From Bancroft, Ontario, Canada. In the Loolekop carbonatite, Transvaal, South Africa. Additional localities are known.
| Category: | Nesosilicates |
| Chemical Formula: | (Mg,Fe2+)5(SiO4)2(F,OH)2 |
| Magnesium Iron Silicate Fluoride Hydroxide | |
| Molecular Weight: | 382.12 gm |
| Composition: | Magnesium | 23.85 % | Mg | 39.55 % | MgO |
| Iron | 18.27 % | Fe | 23.50 % | FeO | |
| Silicon | 14.70 % | Si | 31.45 % | SiO2 | |
| Hydrogen | 0.13 % | H | 1.18 % | H2O | |
| Oxygen | 35.59 % | O | |||
| Fluorine | 7.46 % | F | 7.46 % | F | |
| – % | F | -3.14 % | -O=F2 | ||
| 100.00 % | 100.00 % | = TOTAL OXIDE |
| Crystallography: | Monoclinic – Prismatic |
| Crystal Habit: | Crystals rare, varied in habit, typically flattened || [010], to 10 cm. Commonly as rounded grains, massive. |
| Twinning: | On {001}, common, simple and lamellar; possibly || {015} and {305}. |
| Cleavage: | Indistinct on {100}; parting on {001} |
| Fracture: | Conchoidal |
| Tenacity: | Brittle |
| Moh’s Hardness: | 6.0 – 6.5 |
| Density: | 3.1 – 3.2 (g/cm3) |
| Luminescence: | Not all specimens exhibit fluorescence. Fluorescent specimens show orange yellow under SW UV, orange under LW UV. |
| Radioactivity: | Not Radioactive |
| Color: | Light yellow, yellow, brown, red; in thin section, pale yellow or brown to colorless |
| Transparency: | Transparent to translucent |
| Luster: | Vitreous to resinous |
| Refractive Index: | 1.592 – 1.675 Biaxial ( + ) |
| Birefringence: | 0.027 – 0.032 |
| Dispersion: | Weak to strong; r > v |
| Pleochroism: | X = colorless, very pale yellow, brownish yellow; Y = colorless, yellow-green; Z = colorless, pale green |
| Anisotropism: | Fairly strong; color in reflected light: white |
