Macdonaldite | |
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General | |
Category | Phyllosilicate |
Formula (repeating unit) | BaCa4Si16O36(OH)2·10H2O |
IMA symbol | Mcd [1] |
Strunz classification | 9.EB.05 |
Crystal system | Orthorhombic |
Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Cmcm |
Unit cell | a = 14.06 Å, b = 23.52 Å, c = 13.08 Å; Z = 4 |
Identification | |
Color | Colorless, white |
Crystal habit | Acicular also fibrous, in radiating aggregates; granular |
Cleavage | {010} perfect, {001} good, {100} indistinct |
Mohs scale hardness | 3.5–4.0 |
Luster | Vitreous – silky |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.27 |
Optical properties | Biaxial (+/−), surface relief – low, |
Refractive index | nα = 1.518 nβ = 1.524 nγ = 1.530 |
Birefringence | 0.012 |
2V angle | Measured: 90° |
Dispersion | Weak |
References | [2] [3] [4] [5] [6] |
Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4Si16O36(OH)2·10H2O. [7] Macdonaldite was first described in 1965 and named for Gordon A. Macdonald (1911–1978) an American volcanologist at the University of Hawaii. [7]
Macdonaldite crystallises in the orthorhombic system. Macdonaldite is anisotropic with low relief. [8]
Macdonaldite appears as veins and fracture coatings in a sanbornite and quartz bearing metamorphic rock. Macdonaldite was first described in 1965 for an occurrence near the Big Creek-Rush Creek area in Fresno County, California. It has also been reported from Mariposa and Tulare counties in California. [4] [7] It has also been reported from a quarry in San Venanzo, Umbria, Italy. [4]
Macdonaldite | |
---|---|
General | |
Category | Phyllosilicate |
Formula (repeating unit) | BaCa4Si16O36(OH)2·10H2O |
IMA symbol | Mcd [1] |
Strunz classification | 9.EB.05 |
Crystal system | Orthorhombic |
Crystal class | Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) |
Space group | Cmcm |
Unit cell | a = 14.06 Å, b = 23.52 Å, c = 13.08 Å; Z = 4 |
Identification | |
Color | Colorless, white |
Crystal habit | Acicular also fibrous, in radiating aggregates; granular |
Cleavage | {010} perfect, {001} good, {100} indistinct |
Mohs scale hardness | 3.5–4.0 |
Luster | Vitreous – silky |
Streak | White |
Diaphaneity | Transparent to translucent |
Specific gravity | 2.27 |
Optical properties | Biaxial (+/−), surface relief – low, |
Refractive index | nα = 1.518 nβ = 1.524 nγ = 1.530 |
Birefringence | 0.012 |
2V angle | Measured: 90° |
Dispersion | Weak |
References | [2] [3] [4] [5] [6] |
Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4Si16O36(OH)2·10H2O. [7] Macdonaldite was first described in 1965 and named for Gordon A. Macdonald (1911–1978) an American volcanologist at the University of Hawaii. [7]
Macdonaldite crystallises in the orthorhombic system. Macdonaldite is anisotropic with low relief. [8]
Macdonaldite appears as veins and fracture coatings in a sanbornite and quartz bearing metamorphic rock. Macdonaldite was first described in 1965 for an occurrence near the Big Creek-Rush Creek area in Fresno County, California. It has also been reported from Mariposa and Tulare counties in California. [4] [7] It has also been reported from a quarry in San Venanzo, Umbria, Italy. [4]