LEGRANDITE: Mexico (~ 2, rough 1½ inches long)
This mineral was first described in 1932, and it has become a very popular specimen mineral with collectors because of its intense yellow color and esthetic crystal groupings. It is too soft for wear, but the yellow color is unique among gems and very distinctive. This is one of the loveliest of all the rare collector gemstones.
Legrandite Value
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Legrandite Information
| Data | Value |
| Name | Legrandite |
| Crystallography | Monoclinic. Crystals prismatic, also in sprays and fans. |
| Colors | Yellow, colorless. |
| Luster | Vitreous. |
| Hardness | 4.5. |
| Density | 3.98-4.04. |
| Birefringence | 0.060. |
| Cleavage | Poor. Fracture uneven. Brittle. |
| Stone Sizes | The maximum to expect in a cut legrandite is about 2-4 carats, although a 10-carat stone has been reported! A larger stone would be a great rarity, and even 1 carat gems are very hard to find. Many mineral specimens exist, but transparent crystals are extremely rare even in the source locality. |
| Luminescence | None. |
| Spectral | Not diagnostic. |
| Formula | Zn2(OH)AsO4 · H2O. |
| Pleochroism | Colorless to yellow. |
Optics: a = 1.675-1.702; β= 1.690-1.709; γ= 1.735-1.740.
Biaxial (+), 2V= 50°.
Occurrence: In vugs in limonite. Only occurrence is in Mexico.
Flor de Pena Mine, Nuevo Leόn, Mexico: first discovered locality.
Ojuela Mine, Mapimi. Mexico: best-known locality, from which come magnificent crystal clusters, single crystals up to 6 cm long and 7.5 mm thick. This is the source of the only cuttable material.
Comments: This mineral was first described in 1932, and it has become a very popular specimen mineral with collectors because of its intense yellow color and esthetic crystal groupings. It is too soft for wear, but the yellow color is unique among gems and very distinctive. This is one of the loveliest of all the rare collector gemstones.
Name: After a Belgian mine manager, Mr. Legrand, who collected the first specimens.
