Labradorite

UNB-2017-0115Minerals » Tectosilicates

Description

Five samples of Labradorite that shows a play of colours. Some samples are cut and polished. Labradorite (NaAlsi3O8 (Albite) or CaAl2Si2O8 (Anorthite)) is part of the Plagioclase Feldspar Group and is the name given when there is a play of colours on the mineral. Lustre is vitreous but can be pearly on the cleavage and streak is white. Hardness is 6 and cleavage is good in two direction at nearly right angles and is poor in a third direction. Twinning striations are often seen on the cleavages and the cleavages can be curved. Plagioclase is usually founded as flattened thin blades (variety of Albite) but can also be lamellar, granular, disseminated or rosettes.

Specifications

Object name	Labradorite
ID	UNB-2017-0115
Legal status	Permanent collection
Category	Mineral
Classification	Mineral group: Tectosilicates
Composition	CaB2Si2O8(OH,F)2 (Ca,Na2,K2)Al2Si4O12•6H2O (Ca,Na)AlSi2O8 (Na2,K2)Al2Si4O12•2H2O (Na,Ca)4(Al,Na)3Si9O24(Cl,CO3)2 (MAlO2)(SiO 2)x(H2O)y (Na,K)AlSiO4 Na2Al2Si3O10·2H2O KAlSi3O8 Na2Ca2Al6Si9O30·8H2O K(AlSi2O6) CaAl2Si4O12·4H2O Pectolite NaCa2Si3O8(OH)2H2O with trace amounts of copper (Ca,Na)(Al,Si)4O8 SiO2 with water inclusion (Na,Ca)4-8Al6Si6(O,S)24(Cl,SO4)1-2 Na8(Al6Si6O24)Cl2 CaAl2Si3O10·3H2O SiO2 (Cs,Na)2Al2Si4O12·2H2O (Na, Ca)(Al, Si)AlSi2O8 KAlSi3O8 (Na,K)AlSi3O8 (Na,K)AlSi3O8 CaAl2Si2O8 SiO2
Origin	Unknown
Pieces	5
Partial	No
Measurements	13cm x 8cm x 3.5cm 12.5cm x 7cm x 5cm 16cm x 7cm x 3cm 5.5cm x 5cm x 1cm 10cm x 8.5cm x 0.5cm

Publications

Chesterman, C.W. 1979. Audubon Society, Field Guide to North American Rocks and Minerals. Knopf.