Hemimorphite

Hemimorphite is found in a variety of colors including blue-green, green, white, colorless, brown and yellow. Discovered in 1853, Hemimorphite was originally named 'Calamine'. However, as the name had already been used for another mineral, it was renamed Hemimorphite after its hemimorphic crystal structure. 'Hemi' means 'Half', while 'Morph' means 'Shape'. Hemimorphic crystals produce a different termination at each end of the crystal; thus the term hemimorphic or half shape. Other minerals with hemimorphic crystal structure are Tourmaline, Greenockite, Wurzite and Zincite. However, none of these show the complete structure as found in Hemimorphite.

Hemimorphite is formed from Hydrated Zinc Silicate Hydroxide (Zn4 Si2 O7 (OH)2 -H2O). With its Zinc concentration, Hemimorphite is commonly used as a source of minor ore of zinc. Hemimorphite has a hardness of approximately 5 on the Moh’s Scale of Hardness and an average Specific Gravity of 3.4.

Hemimorphite occurs as veins and beds in calcareous rocks. It is commonly found associated with Hydrozincite, Limonite, Aurichalcite, Calcite and Smithsonite. First discovered in Romania, notable occurrences of Hemimorphite include: Santa Eulalia and Mapimi, Mexico; New Mexico and New Jersey, USA; England and Zambia.

Commonly found in two distinct crystal forms, Hemimorphite is noted for its magnificent "sprays" and clusters of very glassy, clear or white, thin, bladed crystals which are prominently displayed in nearly every mineral museum in the world. The other form produces a blue to blue-green botryoidal crust that resembles Smithsonite or Prehnite. For a serious collector both forms are a must in their mineral collections.