Mauve Vesuvianite MineJeffrey Quebec Canada

Vesuvianite, also known as idocrase, is a green, brown, yellow, or blue silicate mineral. Vesuvianite occurs as tetragonal crystals in skarn deposits and limestones that have been subjected to contact metamorphism.[3] It was first discovered within included blocks or adjacent to lavas on Mount Vesuvius, hence its name. Attractive-looking crystals are sometimes cut as gemstones. Localities which have yielded fine crystallized specimens include Mount Vesuvius and the Ala Valley near Turin, Piedmont.[5]

Vesuvianite

Vesuvianite from the Jeffrey Mine in Asbestos, Quebec

General

Category

Sorosilicate

Formula

(repeating unit)

Ca10(Mg, Fe)2Al4(SiO4)5(Si2O7)2(OH,F)4

IMA symbol

Ves[1]

Strunz classification

9.BG.35

Crystal system

Tetragonal

Crystal class

Ditetragonal dipyramidal (4/mmm)

H-M symbol: (4/m 2/m 2/m)

Space group

P4/nnc

Unit cell

a = 15.52 Å, c = 11.82 Å

Z = 2

Identification

Color

Yellow, green, brown; colorless to white, brown-black, light green, emerald green, violet, blue-green to blue, pink, purple, red, black, commonly zoned

Crystal habit

Short pyramidal to long prismatic crystals common, massive to columnar

Twinning

Fine twin domains observed

Cleavage

Poor on {110} and {100} very poor on {001}

Fracture

Sub conchoidal to irregular

Tenacity

Brittle

Mohs scale hardness

6–7

Luster

Vitreous to resinous

Streak

White

Diaphaneity

Subtransparent to translucent

Specific gravity

3.32–3.43

Optical properties

Uniaxial (−)

Refractive index

nω = 1.703–1.752

nε = 1.700–1.746

Birefringence

0.004–0.006

Pleochroism

slight in colored varieties

Solubility

Vesuvianite is virtually insoluble in acids

Other characteristics

striated lengthwise.