Earth Sciences
Collections

Amethyst

UNB-2017-0252Minerals » Tectosilicates

Description

Sample of numerous, small, dark purple euhedral prismatic Amethyst crystals that are terminated by double rhombohedrons. Visible inclusions in many of the crystals. Vitreous is lustre. Average Amethyst crystal size: 0.3 cm x 0.4 cm x 0.4 cm. Quartz (SiO2) can come in a large variety of colours and when it is purple it is known as Amethyst. Lustre can be vitreous or greasy and streak is white. Hardness is 7. Quartz usually occurs as long or short prismatic crystals that are terminated by a double rhombohedron and have striations crosswise. Quartz can also be massive, granular or disseminated.

Specifications

Object nameAmethyst
IDUNB-2017-0252
Legal statusPermanent collection
CategoryMineral
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
OriginUnknown
Pieces1
PartialNo
Measurements
  • 3.8cm x 6.2cm x 3cm

Publications

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