Chondrodite

Discovered in 1817; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

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

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/B.04-20

Nickel-Strunz 10th Ed. ID:

9.AF.45

9 : SILICATES (Germanates)
A : Nesosilicates
F : Nesosilicates with additional anions; cations in [4], [5] and/or only [6] coordination

Related to:

Humite Group. Dimorph of Ribbeite. Isostructural with Alleghanyite, Chegemite, Edgrewite, Hydroxylchondrodite, Hydroxylclinohumite, Kumtyubeite, Manganhumite, Norbergite, Reinhardbraunsite, Sonolite.

Members of Group:

Humite Group: Alleghanyite, Chegemite, Chondrodite, Clinohumite, Edgrewite, Humite, Hydroxylchondrodite, Hydroxylclinohumite, Jerrygibbsite, Kumtyubeite, Leucophoenicite, Manganhumite, Norbergite, Reinhardbraunsite, Ribbeite, Sonolite

Varieties:

None

Synonyms:

Brocchite, Brucite (of Gibbs), Condrodite, Fluosiderite (F-rich Chondrodite), ICSD 15180, Maclureite (of Nuttall), PDF 12-52, Prolectite

Crystal Data

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}.

Physical Properties

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

Optical Properties

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

Occurances

Geological Setting:

In contact metamorphic zones, in limestones and dolostones, associated with felsic to alkalic plutonic rocks, especially with Fe-B-F metasomatism; in a carbonatite.

Common Associations:

Phlogopite, Spinel, Magnetite, Grossular, Wollastonite, Forsterite, Monticellite, Cuspidine, Diopside, Calcite

Common Impurities:

Ti, Al, Mn

Type Locality:

Skräbböle quarry, Pargas (Parainen), Southwestern Finland Region, Finland

Year Discovered:

1817

View mineral photos:

Chondrodite Mineral Photos and Locations

Unusual Gem Categories

Fluorescent Gems

More Information

Mindat.org
Webmineral.com

Chondrodite is a member of the Humite Group of minerals that includes Chondrodite, Clinohumite, Humite and Norbergite. Faceted Chondrodite is fairly rare. Faceted gems can be beautiful in colors of light yellow, yellow, brown and deep red to deep orangish red. Some Chondrodite gems may exhibit fluorescence of orangish-yellow under shortwave (SW) UV light and orange under longwave (LW) UV light. If you hover your cursor over the picture above, you will see the Chondrodite gem exhibiting fluorescence under UV light.

Chondrodite was named in 1817 by Swedish historian Baron Abraham Constantin Mouradgea d'Ohsson (1779-1851) from the Greek word Χόνδρος (chondros) meaning grain in allusion to its habit of occurring in isolated grains. d'Ohsson called Chondrodite "a yellow stone from Pargas".

There are several sources of Chondrodite around the world, but only a few produce facetable crystals. One source 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 the USA, fine crystals from the Tilly Foster mine, Brewster, Putnam County, and Amity, Orange County, 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. A few other localities are known.

Chondrodite gems for sale:

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