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Amethyst

UNB-2020-0009Minerals » Tectosilicates

Description

Original Description: *Incomplete Amethyst (SiO2) is the purple variety of Quartz. Lustre is vitreous or greasy and streak is white. Hardness is 7. Quartz usually occurs as prismatic crystals that are terminated by double rhombohedrons with striations crosswise. Quartz can also be disseminated, granular or massive. NOTE: May be same file as 2026-0102, which has more complete information

Specifications

Object name Amethyst
IDUNB-2020-0009
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
OriginBrazil
Pieces1
PartialNo

Map of Origin

Publications

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