Lawsonite
Lawsonite is definitely a rare mineral that is silicate is only found in a few places worldwide. Gems are extremely rare and certainly will be attractive with colorless, pale blue or pinkish colors and dispersion that is strong. Lawsonite is a hydrous calcium aluminum sorosilicate mineral together with formula CaAl2Si2O7(OH)2·H2O. Lawsonite crystallizes among the orthorhombic system into prismatic, frequently tabular crystals. Crystal twinning is common. It forms transparent according to translucent colorless, white, and bluish in imitation of pinkish gray glassy in conformity with greasy crystals. Refractive indices are nα=1.665, nβ=1.672 – 1.676, and nγ=1.684 – 1.686. It is normally nearly black within a thin section, however, some lawsonite is pleochroic from colorless in imitation of pale yellow to pale blue, relying upon orientation. The temperament has a Mohs solidity over 8 and a specific gravity concerning 3.09. It has Felicitous cleavage among couple directions and a brittle fracture.
Lawsonite is a metamorphic mineral typical of the blueschist facies. It also occurs so an unimportant mineral within altered gabbro yet diorite. Associate minerals consist of epidote, titanite, glaucophane, garnet yet quartz. It is an uncommon constituent on eclogite. It was first described in 1895 because of occurrences in the Tiburon Peninsula, Marin County, California. It used to be named because of geologist Andrew Lawson (1861–1952) over the University regarding California by two regarding Lawson’s graduate students, Charles Palache yet Frederick Leslie Ransome The location that is main gem quality crystals may be the type locality at Reed facility, Tiburon Peninsula, Marin County, California, USA. Other areas include Panoche Pass, San Benito County; in the Pacheco Pass area, Santa Clara County, California, USA; Darrington, Snohomish County, Washington, USA; the Italian and French Alps; and near Tavsanh, Turkey.
| Category: | Sorosilicate |
| Formula: | CaAl2Si2O7(OH)2·H2O |
| Crystallography: | Orthorhombic – Dipyramidal |
| Crystal Habit: | Crystals commonly prismatic, tabular, to 5 cm; also granular, massive. |
| Twinning: | Common on [101], may be lamellar. |
| Cleavage: | [100] Perfect, [010] Perfect, [101] Imperfect |
| Fracture: | Irregular/Uneven |
| Tenacity: | Brittle |
| Hardness (Mohs): | 7.5 |
| Density: | 3.05 – 3.12 (g/cm3) |
| Luminescence: | None |
| Radioactivity: | Not Radioactive |
| Color: | Colorless, White, Grayish Blue, pale Blue, Pinkish |
| Transparency: | Transparent, Translucent |
| Luster: | Vitreous, Greasy |
| Refractive Index: | 1.663 – 1.686 Biaxial ( + ) |
| Birefringence: | 0.0190 – 0.0210 |
| Dispersion: | Strong to Very Strong |
| Pleochroism: | Weak; X = blue, pale brownish yellow; Y = deep bluish green, yellowish green; Z = colorless, yellowish |
