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Amethyst

UNB-2018-0043Minerals » Tectosilicates

Description

Two samples. The small sample has short, euhedral prismatic Amethyst crystals with a vitreous lustre. Larger sample is colourless/slightly purple Amethyst crystals that are subhedral prismatic crystals. *Larger sample is missing. Largest Amethyst crystal size for the smaller sample: 1.0 cm x 0.8 cm x 0.7 cm. Amethyst (SiO2) is the purple variety of Quartz. Lustre is vitreous or greasy and streak is white. Hardness is 7. Quartz usually occurs as long or prismatic crystals that are terminated by double rhombohedrons and have striations crosswise. Quartz can also be granular, massive or disseminated.

Specifications

Object nameAmethyst
IDUNB-2018-0043
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
Pieces2
PartialNo
Measurements
  • 1cm x 2.8cm x 2.7cm
  • 2.2cm x 4cm x 3.3cm

Publications

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