This is the largest hemimorphite in our collection. We managed to find some of this rare gemstone
on our last buying trip and we couldn’t quite believe our luck. Grab it as we
won’t get it again!
Hemimorphite is a rare gem quality form of zinc silicate.
Hemimorphite is very closely associated with Smithsonite, another rare
collector’s gem. For many years, hemimorphite and smithsonite were both classed
together another gemstone called calamine because of the similarity. In 1803 it
was discovered to be two different minerals by mineralogist, James Smithson (of
the Smithsonian Institute). Hemimorphite is a zinc silicate, whilst smithsonite
is a zinc carbonate; zinc silicate Hemimorphite is considered to be rarer than
Smithsonite. . The name ‘hemimorphite’ originates from the Greek words ‘hemi’
and ‘morph’, which respectively translate as ‘half-shape’. The name refers to
its unusual hemimorphic crystal form, which means that the axial ends of
crystals are asymmetrical. One end of each crystal is rather blunt, dominated
by a pedion (a single face), while the other is pointed and pyramidal.
Hemimorphite can be identified by its distinct composition and unique crystal
structure. Hemimorphite can be composed of over fifty percent zinc.
Gemmologically, it has a refractive index of 1.614 to 1.636 and a density or
specific gravity of 3.30 to 3.50. Its hardness is 5 on the Mohs scale. Few
deposits of Hemimorphite yield gemstone quality materials. Some of the most significant
deposits are from Vieille Montagne, Belgium and Aachen, Germany, Mexico, Russia
(Siberia), The Congo, Namibia, Madagascar and the United States, including
Pennsylvania, Montana, Colorado and New Mexico. Hemimorphite can occur in
various tones of blue, green and colorless. Most gemstones are blue to
blue-green, and look similar to chrysocolla or turquoise. The most desirable
color is sky to Swiss blue, which is reminiscent of Paraiba tourmaline.
Hemimorphite often exhibits bands of blue with white streaks, and it may also
be found interspersed by a dark matrix. Gem quality hemimorphite typically
ranges from transparent to translucent in clarity. There is no known treatment
for this gemstone - it is natural and organic.
Chemical Formula: Zn4Si2O7(OH)2•H2O
- Hydrous basic zinc silicate
Crystal Structure: Orthorhombic;
Blue, green, colorless
5 on the Mohs scale
1.614 to 1.636
3.30 to 3.50
Double Refraction +0.022