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Apophyllite on Stilbite

UNB-2017-0014Minerals » Silicates

Description

Greenish subhedral tabular crystals of Apophyllite with a vitreous lustre that are entwined with white, euhedral "wheat sheaves" of Stilbite. Largest Apophyllite crystal is: 2.6 cm x 1.8 cm x 0.9 cm. Largest Stilbite crystal is: 2.0 cm x 0.6 cm x 0.5 cm. Apophyllite (KCa4Si8O20(F,OH) x H2O) can be colourless, white, grey, greenish, yellowish or reddish in colour. Lustre is vitreous and pearly on the cleavage and streak is white. Hardness is 4 1/2 to 5 and cleavage is perfect in one direction. Apophyllite is usually found as cube-like or tabular form that is square in cross section. Can also be lamellar, granular or compact. Stilbite (NaCa2Al5Si13O36 x 16H2O) can be white, greyish, yellowish, red or brown in colour. Lustre is vitreous and pearly on the cleavage and streak is colourless. Hardness is 3 1/2 to 4 and cleavage is perfect in one direction. Stilbite is usually found as bladed aggregates that resemble "wheat sheaves" but can also be radial, globular or as tabular crystals (rare).

Specifications

Object nameApophyllite on Stilbite
IDUNB-2017-0014
Legal statusPermanent collection
CategoryMineral
Classification
Mineral group:
Silicates
Composition
  • Ca2(Al,Fe)3(SiO4)3(OH)
  • (Al,Fe2+,Fe3+Li,Mg,Mn,Ni)5−6(Al,Fe3+,Si)4(O,OH)18
  • K(Fe,Mg)3AlSi3O10(OH)2
  • BaTiSi3O9
  • (Mg,Fe)2Al3(Si5AlO18)
  • (Ca,Fe,Mg)3Al2BO3Si4O12(OH)
  • Be3Al2(Si6O18)
  • MgSiO3
  • (Mg,Fe2+)5Al(Si3Al)O10(OH)8
  • Na2Fe2+5[Si12O30]
  • (Na,Ca)Fe3+Si2O6
  • NaFe3+Si2O6
  • NaFe3+Si2O6
  • A0-1B2C5T8O22(OH,F,Cl)2
  • (Al,Fe)SiO4
  • Various (e.g., Muscovite - KAl2(AlSi3O10)(OH)2)
  • Al2Si2O5(OH)4
  • Be3Al2(Si6O18)
  • K(Li,Al)3(Al,Si,Rb)4O10(F,OH)2
  • NaAlSi2O6
  • Mg2Si2O6
  • Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
  • Na15Ca6(Fe2+,Mn2+)3Zr3Si25O733(CO3)
  • CaMgSi2O6
  • CaFeSi2O6
  • Ca2Al3(SiO4)3(OH)
  • CaSiO3
  • Ca2(Mg,Fe2+,Fe3+,Al)5(Si,Al)8O22(OH)2
  • (Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)10
  • Na2AlSi3O8·H2O
  • Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2
  • (Na,Ca)(Fe,Mg,Li,Al)3Al6(BO3)3(Si6O18)(OH)4
  • Ca2Al3(SiO4)3(OH)
  • LiAlSi2O6
  • MnSiO3
  • (Mn,Fe)SiO3
  • ADSi2O6
  • Ca2Al(AlSi3O10)(OH)2·H2O
  • (Ca,Na)(Mg,Fe)Si2O6
  • NaCa2Si3O8(OH)2H2O
  • LiAlSi4O10
  • NaAl2(AlSi3O10)(OH)2
  • Mg2Mg5Si8O22(OH)2
  • D3[Si2O5](OH)4
  • Mg3(Si2O5)(OH)4
  • Be₃Al₂(SiO₃)₆
  • A(D3)G6(T6O18)(BO3)3X3Z
  • (Mg,Al)8(Al,Si)6O20
  • SiO2 with variable amounts of water
  • KAl2(AlSi3O10)(F,OH)2
  • Al2(SiO4)O
OriginPouna, Chattisgarh, India
Pieces1
PartialNo
Measurements
  • 4cm x 10.5cm x 3cm

Map of Origin

Publications

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