| Meionite | |
|---|---|
) Meionite (scapolite) crystals (cross-shaped) in a quartz matrix, 7.2 x 4.0 x 3.0 cm. Worcester County, Massachusetts. | |
| General | |
| Category | Tectosilicate Scapolite group |
| Formula (repeating unit) | Ca4Al6Si6O24CO3 |
| Strunz classification | 9.FB.15 |
| Crystal system | Tetragonal |
| Crystal class | Dipyramidal (4/m) (same H-M symbol) |
| Space group | I4/m |
| Unit cell | a = 12.179(1) Å, c = 7.571(1) Å, Z = 2 |
| Identification | |
| Color | Colorless, white, grey, pink, violet, blue, yellow, orange-brown, brown |
| Cleavage | Distinct/good on {100}{110} |
| Fracture | Irregular/uneven, conchoidal |
| Tenacity | Brittle |
| Mohs scale hardness | 5 - 6 |
| Luster | Vitreous, resinous, pearly |
| Streak | White |
| Diaphaneity | Transparent, opaque |
| Specific gravity | 2.74 - 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
- ^ Mineralienatlas
- ^ Mindat.org
- ^ Webmineral.com
- ^ Handbook of Mineralogy
- ^ 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.