Meionite

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Meionite
Meionite-Quartz-53866.jpg
Meionite (scapolite) crystals (cross-shaped) in a quartz matrix, 7.2 x 4.0 x 3.0 cm. Worcester County, Massachusetts.
General
CategoryTectosilicate
Scapolite group
Formula
(repeating unit)
Ca4Al6Si6O24CO3
Strunz classification9.FB.15
Crystal systemTetragonal
Crystal classDipyramidal (4/m)
(same H-M symbol)
Space groupI4/m
Unit cella = 12.179(1) Å,
c = 7.571(1) Å, Z = 2
Identification
ColorColorless, white, grey, pink, violet, blue, yellow, orange-brown, brown
CleavageDistinct/good on {100}{110}
FractureIrregular/uneven, conchoidal
TenacityBrittle
Mohs scale hardness5 - 6
LusterVitreous, resinous, pearly
StreakWhite
DiaphaneityTransparent, opaque
Specific gravity2.74 - 2.78
References[1][2][3][4]

Meionite is a tectosilicate belonging to the scapolite group with the formula Ca4Al6Si6O24CO3[5]. Some samples may also contain a sulfate group. It was first discovered in 1801 on Mt Somma, Vesuvius, Italy. It was named by Rene Just Haüy after μειωυ, the Greek word for less, in reference to the less acute pyramidal form as compared to Vesuvianite.

References[edit]

  1. ^ Mineralienatlas
  2. ^ Mindat.org
  3. ^ Webmineral.com
  4. ^ Handbook of Mineralogy
  5. ^ Teertstra, David K.; Sherriff, Barbara L. (1997-04-25). "Substitutional mechanisms, compositional trends and the end-member formulae of scapolite". Chemical Geology. 136 (3): 233–260. doi:10.1016/S0009-2541(96)00146-5. ISSN 0009-2541.