| Lansfordite | |
|---|---|
| General | |
| Category | Carbonates |
| Formula (repeating unit) | MgCO3·5H2O |
| IMA symbol | Lfd[1] |
| Strunz classification | 5/D.01-30 |
| Dana classification | 15.1.6.1 |
| Crystal system | Monoclinic |
| Space group | P21/c (No. 14) |
| Unit cell | a=7.3458 Å, b=7.6232 Å, c=12.4737 Å, β=101.722° |
| Identification | |
| Formula mass | 174.39 |
| Colour | Colourless, white after exposure |
| Crystal habit | Crystals, stalactites terminated by crystal faces, efflorescences, parallel growths. |
| Cleavage | Perfect, Distinct |
| Mohs scale hardness | 2.5 |
| Luster | Vitreous (if fresh) |
| Streak | White |
| Diaphaneity | Translucent, opaque after exposure |
| Specific gravity | 1.6 |
| Density | 1.6 |
| Birefringence | 0.042 |
Lansfordite is a hydrated magnesium carbonate mineral with composition: MgCO3·5H2O.[2] Landsfordite was discovered in 1888 in a coal mine in Lansford, Pennsylvania. It crystallizes in the monoclinic system (space group P21/c[3]) and typically occurs as colorless to white prismatic crystals and stalactitic masses.[4] It is a soft mineral, Mohs hardness of 2.5, with a low specific gravity of 1.7. It is transparent to translucent with refractive indices of 1.46 to 1.51.[5] The mineral will effloresce at room temperature, producing nesquehonite.[6]
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