Minerals - Andalusite | TerraCollect

AndalusiteAl₂[O|SiO₄]

Links

Chemical Properties

Mineral Class

Silicates

Toxicity

none

Formula

Al₂[O|SiO₄]

Unit Cell

a=7.80 b=7.90 c=5.56 Z=4

Physical Properties

Hardness

6.5 - 7.5

Streak

white

Density

Normal (2-3,5)

Optical Properties

Color

browngrayredyellowgreengray brown

Birefringence

0.010

Luster

Vitreous

Transparency

translucent,

transparent,

opaque

Pleochroism

X: Rot-Orange-Braun-Pink Y: Grün-Gelb

Geomineralogical Properties

Composition

Elements

Mass

SiO₂

36.74

TiO₂

0.01

Al₂O₃

62.70

Fe₂O₃

0.36

FeO

0.05

CuO

0.02

MgO

0.03

Map-Layer

Geological MapSatellite Map

Name and first discovery : Named in 1798 by Jean-Claude Delamétherie (1743-1817) after the type locality, although this is not located in Andalusia.

Chemistry : Polymorphic with kyanite and sillimanite

Abbreviation : And

literature

Dana, J. D., & Dana, E. S. (1892). The system of mineralogy of James Dwight Dana, 1837-1868: descriptive mineralogy . J. Wiley & sons.

Cleavage

Good after {110}, poor after {100}

Fracture

conchoidal,

uneven

Tenacity

Brittle

Crystal System

orthorhombic

Point Group

orthorhombic-dipyramidal - 2/m 2/m 2/m

Space Group

Pnnm (58)

Habit

blocky, granular, prismatic

Formation

(1) Primarily metamorphosed under low pressures and low to medium temperatures during contact or regional low-pressure metamorphism of aluminum-rich, pelitic sediments (metapelites), and (2) magmatically as a late crystallization phase in aluminum-supersaturated granitoids and their pegmatites

Paragenesis

Twinning

Rare after {101}

Rarity

Common

Synonyms

Andalusite, Andaluzite, Apyre, Lohestite

Varieties

Chiastolith, Viridin, Titan-Andalusit

K₂O

0.07

H₂O

0.16

Idaho (Dana 1892)

Mineral - Andalusite

Map-Layer