Hemimorphite is Hydrated Zinc Silicate Hydroxide Zn4Si2O7(OH)2·(H2O). This mineral is categorized as one of the Sorosilicates because it contains two silicate tetrahedrons in its structure. Hemimorphite varies in color and can either be colorless, white, brown, yellow, green, or blue like these botryoidal (shaped like a bunch of grapes) crystalline crusts I photographed at the Arizona-Sonora Desert Museum.
Hemimorphite gets its name from the hemimorphic structure of its crystals. Hemimorphic crystals have asymmetrical ends. Hemimorphite crystals are definitely asymmetrical with one blunt end and one pointed end.
Hemimorphite is transparent to translucent with a Mohs' hardness of 5, a specific gravity of 3.45, and a white streak when scraped on an unglazed ceramic plate. Hemimorphite crystals are found in two mains forms, either as well-formed, glassy crystals or as botryoidal crusts.