Crystal Brown Jasper

Category

Carbonate mineral

Formula
(repeating unit)

CaCO3

Strunz classification

5.AB.15

Crystal system

Orthorhombic

Crystal class

Dipyramidal (mmm) 
H-M symbol: (2/m 2/m 2/m)

Space group

Pmcn

Unit cell

a = 4.95, b = 7.96 
c = 5.74 [Å]; Z = 4

Identification

Color

White, red, yellow, orange, green, purple, grey, blue and brown

Crystal habit

Pseudohexagonal, prismatic crystals, acicular, columnar, globular, reniform, pisolitic, coralloidal, stalactitic, internally banded

Twinning

Polysynthetic parallel to {100} cyclically on {110}

Cleavage

Distinct on {010}, imperfect {110} and {011}

Fracture

Subconchoidal

Tenacity

Brittle

Mohs scalehardness

3.5-4

Luster

Vitreous, resinous on fracture surfaces

Streak

White

Diaphaneity

Translucent to transparent

Specific gravity

2.95

Optical properties

Biaxial (-)

Refractive index

nα = 1.529 - 1.530 nβ = 1.680 - 1.682 nγ = 1.685 - 1.686

Birefringence

δ = 0.156

2V angle

18°

Solubility

Dilute acid

Other characteristics

Fluorescence: pale rose, yellow, white or bluish; phosphorescence: greenish or white (LW UV); yellowish (SW UV)