Tobermorite
Tobermorite | |
---|---|
240px
Crystalline mass of tobermorite
|
|
General | |
Category | Silicate mineral, Calcium silicate hydrate |
Formula (repeating unit) |
Ca5Si6O16(OH)2·4H2O, or; Ca5Si6(O,OH)18·5H2O |
Crystal symmetry | Orthorhombic 2 2 2 |
Unit cell | a = 11.17 Å, b = 7.38 Å, c = 22.94 Å; β = 90°; Z = 4 |
Identification | |
Formula mass | 702.36 |
Color | Pale pinkish white, white, brown |
Crystal habit | As minute laths; fibrous bundles, rosettes or sheaves, radiating or plumose, fine granular, massive. |
Crystal system | Orthorhombic - Disphenoidal |
Cleavage | {001} Perfect, {100} Imperfect |
Mohs scale hardness | 2.5 |
Luster | Vitreous, silky in fibrous aggregates |
Streak | White |
Diaphaneity | Translucent to translucent |
Specific gravity | 2.423 - 2.458 |
Optical properties | Biaxial (+) |
Refractive index | nα = 1.570 nβ = 1.571 nγ = 1.575 |
Birefringence | δ = 0.005 |
Ultraviolet fluorescence | Fluorescent, Short UV:weak white to yellow, Long UV:weak white to yellow |
References | [1][2][3] |
- Not to be confused with torbernite, a hydrated copper uranyl phosphate.
Tobermorite is a calcium silicate hydrate mineral with chemical formula: Ca5Si6O16(OH)2·4H2O or Ca5Si6(O,OH)18·5H2O.
Two structural varieties are distinguished: tobermorite-11 Å and tobermorite-14 Å. Tobermorite occurs in hydrated cement paste and can be found in nature as alteration mineral in metamorphosed limestone and in skarn. It has been reported from the Maqarin Area of north Jordan and in the Crestmore Quarry near Crestmore Heights, Riverside County, California.
Tobermorite was first described in 1880 for an occurrence in Scotland, on the Isle of Mull, around the locality of Tobermory.[2]
Use in Roman concrete
Aluminium substituted tobermorite is understood to be a key ingredient in the longevity of ancient Roman undersea concrete, as per the American Ceramic Society.[4]
See also
- Other Calcium silicate hydrate minerals:
References
- American Mineralogist (1954) 39, 1038.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
- Lua error in package.lua at line 80: module 'strict' not found.
External links
Wikimedia Commons has media related to Crestmore Quarries. |