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Henmilite
Current inventory:  0 gems
 

Henmilite

  
Henmilite is named to honor Professor Kitinosuke Henmi (19191997), 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:

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