Trigonal
Phenakite is a beryllium nesosilicate, simpler in chemistry than its better-known beryllium relative beryl. Its name comes from the Greek “phenax” (deceiver) because crystals strongly resemble quartz. Phenakite is sought for both rare gem material and its sharp rhombohedral crystals.
Occurrence
Type locality: Emerald Mines, Takovaya River (Russia). Other notable: Itatiaia and Minas Gerais (Brazil), Mt. Antero (Colorado), Volyn (Ukraine), and Erongo (Namibia). Found in pegmatites and high-temperature alpine veins. Chinese material is minor.
Identification
Rhombohedral or short-prismatic crystals + glassy luster + high hardness (~8) + low density. Distinguish from quartz (lower density, hexagonal not trigonal habit when sharp) by careful crystal morphology and density.
Collector Notes
Volyn pegmatite phenakite (Ukraine) and Brazilian crystals are the gem-grade benchmarks. Often paired with beryl, topaz and tourmaline in pegmatite collections.