3.6" Hemimorphite Crystals on Green Smithsonite - Utah

Smithsonite is known to form in earthy botryoidal masses, sometimes forming grape-like structures. It can be found as a secondary mineral in oxidation zones of zinc ore deposits, in some sedimentary deposits and as an oxidation product of sphalerite. The general chemical formula of smithsonite is ZnCO3, however Fe (iron), Mg (magnesium), Ca (calcium), Cd (cadmium), Cu (copper), and Co (cobalt) can take the place of Zn (zinc). This potential for elemental variation results in smithsonite having the ability to exhibit a wide variety of colors including blue, green, yellow, orange, pink, purple, brown, gray, white and colorless.

Hemimorphite is a basic hydrous zinc silicate with the chemical composition Zn4Si2O7(OH)2 · H2O. It earned its name from the structure of which the crystals form, through greek terminology. It has two different terminations on each side of the crystal, hence the inclusion of the greek terms "hemi", meaning half and "morph", meaning shape. The crystal formations can range anywhere between a crystal druze or botryoidal formation, to radiating acicular crystals, and more. The color of these crystals have been found to be white, beige, light brown and blue. On rare occasions, yellow and green crystals have been found.

Prior to 1803, hemimorphite and smithsonite were thought to be the same mineral called "calamine". However, following further scientific research, it was concluded that these were two distinct minerals.