Home > Mexico II Type Locales – December 22 > MS1680 Legrandite

Legrandite - Sold

Legrandite is a hydrated zinc arsenate originally described by Drugman et al. (1932). The mineral name honors Louis C.A. Legrand (1861-1920), a Belgian mining engineer who preserved the type specimen (Van Tichelen, 2016). Legrandite remained a great rarity until its discovery at another locality in Mexico: Mina Ojuela, first recorded in the literature by Switzer (1956). Single crystal X-ray study (Finney, 1963) and chemical analysis (Desautels & Clarke, 1963) of Ojuela material established the modern chemical formula for legrandite: Zn2AsO4OH·H2O. The formula is like that of adamite, simply with an additional molecule of water.

Legrandite from Mina Flor de Peña, the source of this specimen, is much rarer than that from the prolific Mina Ojuela. This specimen features yellow legrandite crystals to 5 mm. Their habit is stubby prismatic with blunt terminations, which is characteristic of the locality (Megaw & Megaw, 2016). The matrix is a boxwork of gray-green smithsonite with minor limonite.