Henmilite
Current inventory:  0 gems
 

  
Henmilite is named to honor Professor Kitinosuke Henmi (1919–1997), and his daughter Dr. Chiyoko Henmi (1949– ), Department of Earth Science, Okayama University, Okayama, Japan, in recognition of their mineralogical work on the skarn deposit at Fuka, Japan.

Discovered in 1981;   IMA status:  Valid (IMA approved 1986)

Chemistry

Chemical Formula:

Ca₂CuB₂(OH)₁₂

Calcium Copper Hydroborate Hydroxide

Molecular Weight:

369.41 gm

Composition:

Calcium

21.70 %

Ca

30.36 %

CaO

Copper

17.20 %

Cu

21.53 %

CuO

Boron

5.85 %

B

18.85 %

B₂O₃

Hydrogen

3.27 %

H

29.26 %

H₂O

Oxygen

51.97 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Borates

Strunz 8th Ed. ID:

5/G.09-20

Nickel-Strunz 10th Ed. ID:

6.AC.30

6 : BORATES
A : Monoborates
C : B(O,OH)₄, without and with additional anions; 1(T), 1(T)+OH, etc

Related to:

n/a

Varieties:

None

Synonyms:

IMA 1981-050

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Minute triclinic pinacoidal crystals exhibit {100}, {010}, {101}, {102}, {110}, {011}, {142}, to 3 mm; massive.

Twinning:

None

Physical Properties

Cleavage:

None

Fracture:

Fragile

Tenacity:

Fragile

Moh's Hardness:

1.5 - 2.0

Density:

2.51 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Bluish-Violet

Transparency:

Transparent

Luster:

Vitreous

Refractive Index:

1.585 - 1.615  Biaxial  ( - )

Birefringence:

0.0300

Dispersion:

n/a

Pleochroism:

Strong; X = pale pink; Y = pale purple; Z = very pale blue

Occurances

Geological Setting:

Very rare, in cavities in borate veins in contact-metasomatized limestone.

Common Associations:

Pentahydroborite, Tenorite, Sillenite, Bultfonteinite, Cuspidine, Thaumasite, Brucite, Calcite

Common Impurities:

n/a

Type Locality:

Fuka mine, Bitchu-cho (Bicchu-cho), Takahashi, Okayama Prefecture, Chugoku Region, Honshu Island, Japan

Year Discovered:

1981; IMA approved 1986

View mineral photos:

Henmilite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Henmilite is a very rare borate mineral that comes from only one location in the world; the Fuka mine, near Bicchu-cho, Takahashi, Okayama Prefecture, Chugoku Region, Honshu Island, Japan. The crystals are usually very small, to about 3 mm, and a very beautiful vivid bluish violet to purple color. Faceted gems are extremely rare due to the small size of the crystals, the fact that they are very soft (Mohs hardness of 1.5 - 2.0) and they are very fragile.
 

  
Henmilite gems for sale:

We have not photographed our Henmilite gems. Please check back soon.