Goosecreekite | |Ca2(H2O)10| [Al4Si12O32] | ![]() Rough crystals of goosecreekite, each about 3 cm long, from quarries on Malegaon hill, Nasek, India |
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Morphology: | |||
Tabular parallel to {010} to 8 cm; in groups of nearly parallel crystals | |||
Physical properties: | |||
Cleavage: {101}
perfect Hardness: 4.5 Density: 2.21 g/cm3 Luster: vitreous to pearly Streak: white |
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Optical properties: | ![]() |
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Color: colorless to white; colorless in thin section. Biaxial (- or +). α = 1.495, β = 1.498, γ = 1.502, δ = 0.007, 2Vx = 82°. Z ˄ c = 46°, Y = b. O.A.P || (010) |
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Crystallography: | |||
Unit cell data: a 7.401 Å b 17.439 Å c 7.293 Å β 105.44° Z = 1, Space group P21 |
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Name: | |||
Goosecreekite was described and named by Dunn et al. (1980) for the type locality at the Goose Creek quarry, Leesburg, Loudoun County, Virginia, U.S.A. | |||
Crystal structure: | |||
The framework of goosecreekite (GOO) consists of almost completely ordered (Si,Al) tetrahedra (Rouse and Peacor 1986). In the accompanying figure green tetrahedra are AlO4 and the gray are SiO4. |
Chemical composition: |
There is only one published analysis for goosecreekite (Dunn et al. 1980). The ordered structure yields the TSi value of 0.75. Unpublished data show no cations other than Ca in samples from India. |