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Hemimorphite
Current inventory:  1 gem
 

Chemistry:  Zn₄Si₂O₇(OH)₂·(H₂O)   [Hydrated Zinc Silicate Hydroxide]

Discovered in 1853;   IMA status: Valid (pre-IMA; Grandfathered).
Hemimorphite is named in allusion to the hemimorphic form of the crystals.

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/C.08-10

Nickel-Strunz 10th Ed. ID:

9.BD.10

9 : SILICATES (Germanates)
B : Sorosilicates
D : Si₂O₇ groups, with additional anions; cations in tetrahedral [4] and greater coordination

Related to:

Hemimorphite - Junitoite Series

Crystal Data

Crystallography:

Orthorhombic - Pyramidal

Crystal Habit:

Commonly crystallized, thin tabular, striated, to 10 cm; doubly-terminated crystals show hemimorphism. Typically in sheaf-like or fan-shaped aggregates; stalactitic, mammillary, botryoidal; as compact fibrous and chalky coatings.

Twinning:

On [001], rare, with antilogous poles in contact.

Physical Properties

Cleavage:

[110] Perfect

Fracture:

Uneven to Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.5 - 5.0

Density:

3.40- 3.50 (g/cm³)

Luminescence:

May be bluish under SW UV.

Radioactivity:

Not Radioactive

Other:

Strongly Pyroelectric

Optical Properties

Color:

Colorless, white, grey, yellow, green to apple-green, blue, pink, purple, bluish grey, and brown from impurities

Transparency:

Transparent to Translucent

Luster:

Vitreous, Subpearly, Adamantine, rarely Silky

Refractive Index:

1.614 - 1.636  Biaxial ( + )

Birefringence:

0.022

Dispersion:

Strong; r > v

Pleochroism:

None

Occurances

Geological Setting:

A secondary mineral in the oxide zones of ore deposits and in veins and beds in stratified calcareous rocks.

Common Associations:

Anglesite, Aurichalcite, Calcite, Chrysocolla, Cerussite, Galena, Hydrozincite, Rosasite, Smithsonite, Sphalerite

Common Impurities:

Cu, Fe

Type Locality:

Baita Mining District (Baita Bihor; Rézbánya), Nucet, Bihor Co., Romania

Year Discovered:

1853

View mineral photos:

Hemimorphite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Hemimorphite is somewhat common as mineral specimen but rarely faceted due to lack of clean crystals. It is usually available as cabochons in beautiful shades of blue from Congo. There are several sources throughout the southwestern US and Mexico. However, faceted gems are only available from Mexico thus far and are usually colorless. Facetable crystals are rarely available from Mapimi, Durango, and Santa Eulalia, Chihuahua.
 

  
Hemimorphite gems for sale: