User:Strickja/Scolecite New
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Scolecite is a tectosilicate mineral belonging to the zeolite group; it is a hydrated calcium silicate, CaAl2Si3O10.3H2O. Only minor amounts of sodium and traces of potassium substitute for calcium. There is an absence of barium, strontium, iron and magnesium[1] [5]. Scolecite is isostructural (having the same structure) with the sodium-calcium zeolite mesolite and the sodium zeolite natrolite, but it does not form a continuous chemical series with either of them[1]. It was described in 1813, and named from the Greek word, σκώληξ = 'worm' because of its reaction to the blowpipe flame.
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Scolecite | |
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General | |
Category | Zeolites |
Formula (repeating unit) | CaAl2Si3O10.3H2O |
Strunz classification | 8/J.21-60 or ID: 9.GA.05 |
Dana classification | 77.1.5.5 |
Crystal system | Monoclinic m Space group Cc |
Identification | |
Formula mass | 392.34 g |
Color | Colorless white, pink, salmon, red or green |
Crystal habit | Thin prismatic needles, radiating groups and fibrous masses |
Twinning | Common on {100}, twin axis [001], rare on {001} and {110} [1] |
Cleavage | Perfect on {110} and {110} |
Fracture | Irregular/uneven |
Tenacity | Brittle |
Mohs scale hardness | 5 to 5½ |
Luster | Vitreous, silky when fibrous |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.16 to 2.40 |
Optical properties | Biaxial (-) |
Refractive index | Nx = 1.507 to 1.513 Ny = 1.516 to 1.520 Nz = 1.517 to 1.521 |
Pleochroism | X: colourless Y: colourless Z: colourless [2] |
Solubility | Soluble in common acids. |
Other characteristics | Pyroelectric and piezoelectric, sometimes fluorescent yellow to brown in LW and SW UV. Not radioactive. |
References | [1] [3] [2] [4] |