Johachidolite
Current inventory:  1 gem
 

  
Johachidolite is named after its type locality, Johachido District, North Korea, an obsolete Japanese colonial-era name for the locality now known as Sangpal-tong, Changbaeng-myon, Kilchu-gun, North Hamgyong Province, North Korea.

Discovered in 1942;   IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

CaAlB₃O₇

Calcium Aluminum Borate

Molecular Weight:

211.49 gm

Composition:

Calcium

18.95 %

Ca

26.52 %

CaO

Aluminum

12.76 %

Al

24.11 %

Al₂O₃

Boron

15.33 %

B

49.38 %

B₂O₃

Oxygen

52.96 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Borates

Strunz 8th Ed. ID:

5/L.03-10

Nickel-Strunz 10th Ed. ID:

6.CC.05

6 : BORATES
C : Triborates
C : Phyllo-triborates

Related to:

n/a

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

Equant subhedral crystals, to 1 mm, typically granular and lamellar masses.

Twinning:

None

Physical Properties

Cleavage:

On {201}, a parting.

Fracture:

Subconchoidal

Tenacity:

Brittle

Moh's Hardness:

7.5

Density:

3.37 - 3.45  (g/cm³)

Luminescence:

Some specimens show strong whitish-blue fluorescence under LW UV and pale blue to purple fluorescence under SW UV, with weak phosphorescence

Radioactivity:

Not Radioactive

Optical Properties

Color:

Colorless, White, Pale Yellow, Yellow

Transparency:

Transparent to Translucent

Luster:

Vitreous (glassy)

Refractive Index:

1.712 - 1.729  Biaxial ( + )

Birefringence:

0.0140

Dispersion:

Relatively Strong; r > v

Pleochroism:

None

Occurances

Geological Setting:

In a nepheline dike cutting limestone (Johachido district, North Korea).

Common Associations:

Scapolite, Diopside, Albite, Nepheline, Apatite, Phlogopite (Johachido district, North Korea).

Common Impurities:

None

Type Locality:

Sangpal-tong, Changbaeng-myon, Kilchu-gun, (Johachido District), Hodu Prefecture, North Hamgyong Province, North Korea

Year Discovered:

1942; redefined by the IMA as a new mineral in 1977

View mineral photos:

Johachidolite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Johachidolite is an very rare borate mineral that until a recent find in Mogok, Myanmar (Burma) was only found in minute grains no larger than 1 mm in North Hamgyong Province, North Korea. The first faceted gem was created in 1998 from a pale yellow crystal found in the Mogok region (see Journal of Gemmology, 1999, Vol. 26, no. 5). There are currently just a small amount of gems in existence and the only source is the recent find in Mogok.
 

  
Johachidolite gems for sale: