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Idocrase

 

Vesuvianite (also known as Idocrase)

 

Discovered in 1795; IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

(Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)10

 

Calcium Aluminum Magnesium Iron Silicate Hydroxide

Molecular Weight:

1,422.09 gm

Composition:

Calcium

28.18 %

Ca

39.43 %

CaO

 

Magnesium

3.42 %

Mg

5.67 %

MgO

 

Aluminum

7.59 %

Al

14.34 %

Al2O3

 

Silicon

17.77 %

Si

38.03 %

SiO2

 

Hydrogen

0.28 %

H

2.53 %

H2O

 

Oxygen

42.75 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/C.26-10

Nickel-Strunz 10th Ed. ID:

9.BG.35

 

9 : SILICATES (Germanates)
B : Sorosilicates
G : Sorosilicates with mixed SiO
4 and Si2O7 groups; cations in octahedral [6] and greater coordination

Related to:

Vesuvianite Group. Hydroxyl analogue of Fluorvesuvianite.

Members of Group:

Vesuvianite Group: Fluorvesuvianite, Manganvesuvianite, Vesuvianite, Wiluite

Varieties:

Alumovesuvianite, Beryllian Vesuvianite, Californite, Cerian Vesuvianite, Chrome-Vesuvianite, Cyprine, Egeran, Fluorvesuvianite, Frugardite, High-Hydrated Si-Deficient Vesuvianite, Manganidocrase, Magnesiovesuvianite, Manganoan Vesuvianite, Manganvesuvianite, Xanthite

Synonyms:

Gahnite, Genevite, Gökumite, Heteromerite, Hyacinth, Hyacinthine, Idocrase, Jefreinoffite, Jevreinovite, Loboite, Pyramidal Garnet, Vesuviana, Volcanic Chrysotile

 

 

Crystal Data

   

   

Crystallography:

Tetragonal - Dipyramidal

Crystal Habit:

Crystals commonly as short pyramidal to long prismatic crystals, to 15 cm, morphologically complex, with up to 30 forms reported on one crystal; columnar, granular, massive. Californite is found in massive form, not as crystals.

Twinning:

Twinned domains observed at a very fine scale.

 

 

Physical Properties

   

 

Cleavage:

Indistinct on {110}, {100} and {001]

Fracture:

Irregular/Uneven, Sub-conchoidal

Tenacity:

Brittle

Moh's Hardness:

6.0 - 7.0

Density:

3.32 - 3.47 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Green, Brown, Colorless to White, Blue (Cyprine), Violet, Bluish green, Pink, Red, Black, commonly zoned; in transmitted light, Colorless to light Yellow, Green, Brown

Transparency:

Transparent, Translucent

Luster:

Vitreous, Resinous

Refractive Index:

1.698 - 1.742  Uniaxial ( -/+ ) and Biaxial

Birefringence:

0.0040 - 0.0060

Dispersion:

Strong; 0.019 - 0.025

Pleochroism:

Weak; O = colorless to yellowish, E = yellowish, greenish, brownish

 

 

Occurances

   

   

Geological Setting:

In skarns formed during contact or regional metamorphism of limestones; in garnetized gabbros, mafic and ultramafic rocks, and serpentinites; uncommon in alkalic igneous rocks.

Common Associations:

Grossular, Diopside, Wollastonite, Epidote, Scapolite, Spinel, Calcite

Common Impurities:

Fe, Be, B, F, Cu, Li, Na, K, Mn, Ti, Cr, Zn, H2O

Type Locality:

Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy

Year Discovered:

1795

View mineral photos:

Vesuvianite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 

Vesuvianite, also known as Idocrase, is a silicate mineral that is a member of the Vesuvianite mineral group that includes Cyprine, Vesuvianite and Wiluite. Vesuvianite is found in colors ranging from green to brown and also a blue variety called Cyprine. yprine is colored blue by the addition of copper to its chemistry and is also refered to as Cupreous Idocrase or Cupreous Vesuvianite. The complexities of Vesuvianite's chemistry leads to the wide range of colors and properties. The green variety is similar in color to Peridot gems. The name Idocrase is a popular synonym of Vesuvianite. Vesuvianite is an IMA approved mineral name, Idocrase is not.

Vesuvianite was named in 1795 by German geologist Abraham Gottlob Werner (1749-1817) from its discovery locality on Mt. Vesuvius, Campania, Italy. However, Vesuvianite was not this mineral's original name though. It has had many names over its history. It was originally named "hyacinthus dictus octodecahedricus" in 1723 by Swiss naturalist Moritz Anton Kappeler (1685-1769). It was renamed "hyacinte du Vesuve" in 1772 by French mineralogist Jean-Baptiste Louis Romé de L'Isle (1736-1790). It was renamed "hyacinthine" in 1792 by French mineralogist Jean-Claude Delamétherie (1743-1817). It was named "vesuvian" twice, once in 1794 by Irish geologist Richard Kirwan (1733-1812) and again in 1795 by German geologist Abraham Gottlob Werner (1749-1817). Vesuvianite was renamed Idocrase in 1796 by French mineralogist René Just Haüy (1743-1822). The name Idocrase is from the Greek words idos and krasis, meaning mixed appearance due to its varied crystal shapes.

A variety of Vesuvianite from California, USA and has been nick-named Californite or California Jade. This bright green opaque to translucent material comes from near Happy Jack mine, Siskiyou County and near Pulga, Butte County, California.

There are many sources of Vesuvianite such as Asbestos, Quebec, Canada; California, Colorado and the New England region of USA; Mt. Vesuvius, Italy; Ural Mountains, Russia, Switzerland, Tanzania and Kenya. However, there are only a few sources of gem quality crystals. A small amount of gemmy material has come from Asbestos, Quebec, Canada. Recent finds in Tanzania and Kenya have brought some very nicely colored gems to the market.

Vesuvianite gems for sale:

Vesuvianite-001

Gem:

Vesuvianite

Stock #:

VESUV-001

Weight:

1.8070 ct

Size:

8.89 x 6.92 x 3.96 mm

Shape:

Rectangle

Color:

Green

Clarity:

Eye Clean

Origin:

Magadi, Kenya

Treatment:

None (natural)

Price:

SOLD (but we have others)

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Vesuvianite-001

A beautiful Vesuvianite with great color from southern Kenya.

 

Vesuvianite-002

Gem:

Vesuvianite

Stock #:

VESUV-002

Weight:

0.4540 ct

Size:

6.87 x 2.98 x 2.06 mm

Shape:

Rectangle

Color:

Golden Green

Clarity:

Eye Clean

Origin:

Mt. Vesuvius, Italy

Treatment:

None (natural)

Price:

SOLD (but we have others)

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Vesuvianite-002

A very rare gem from the type locality for Vesuvianite; Mt. Vesuvius, Somma-Vesuvius Complex, Naples Province, Campania, Italy.

 

 


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