Click on a letter above to view the list of gems.  

           


Genthelvite
Current inventory:  1 gem
 

Genthelvite

Chemistry:  Zn4Be3(SiO4)3S

Discovered in 1944;   IMA status: Valid (pre-IMA; Grandfathered).
Genthelvite is named after
Frederick August Ludwig Karl Wilhelm Genth (1820-1893), German-American chemist and mineralogist, who described a zinc-rich Helvite (which was later renamed Genthelvite); and its relationship to Helvite.

 

Classification

   

   

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.12-30

Nickel-Strunz 10th Ed. ID:

9.FB.10

 

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H
2O
B : Tektosilicates with additional anions
30 : Helvite Group, Danalite-Genthelvite Series, Danalite-Helvite Series, Genthelvite-Helvite Series

 

 

Crystal Data

   

   

Crystallography:

Isometric - Hextetrahedral

Crystal Habit:

Crystals commonly tetrahedral, up to 5 cm in diameter; also as large rounded grains

Twinning:

None

 

 

Physical Properties

   

 

Cleavage:

[111] Poor

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Hardness (Mohs):

6.0 - 6.5

Density:

3.44 - 3.70 (g/cm3)

Luminescence:

Strong green fluorescence in LW and SW UV; short-lived phosphorescence

Radioactivity:

Not Radioactive

Other:

Gelatinizes with acids

Optical Properties

   

   

Color:

Red, Pink, Colourless, White, Yellow, pale Green to Emerald Green; darkens to Brown and Black on weathering

Transparency:

Transparent, Translucent

Luster:

Vitreous

Refractive Index:

1.738 - 1.752  Isotropic

Birefringence:

0.00  Isotropic

Dispersion:

n/a

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

In miarolitic cavities in granite pegmatites; in alkaline granites and syenites, greisens, and skarns.

Type Locality:

West Cheyenne Canon, Cheyenne District (St. Peters Dome District), El Paso Co., Colorado, USA

Year Discovered:

1944

View mineral photos:

Genthelvite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Genthelvite is an extremely rare mineral and gem that forms a mineral series with Helvite and Danalite. Genthelvite is a member of the Helvine Group of minerals that also includes Danalite
, Genthelvite, Helvine and Tugtupite. Genthelvite was discovered in Cheyenne Canyon, El Paso County, Colorado, USA in 1944 and has since been found in several other locations around the world. Gems are usually very small, less than a quarter carat, and included. Colors include colorless, yellow, green, pink to red and may darken to brown and black from weathering.

The most notable locations for gem quality crystals are Poudrette quarry Mont Saint-Hilaire, Rouville County, Québec, Canada; Bakstevalåsen, Gunhildrud, Øvre Eiker, Buskerud, Norway; Zagi Mountain, Mulla Ghori, Khyber Agency, Federally Administered Tribal Areas (FATA), Pakistan; West Cheyenne Canyon, near St. Peters Dome, El Paso County, Colorado, USA. These locations produce only very small crystals.
 

  
Genthelvite gems for sale:

Genthelvite-001

Gem:

Genthelvite

Stock #:

GENTH-001

Weight:

0.0300 ct

Size:

2.10 x 1.20 x 0.60 mm

Shape:

Marquise (native cut)

Color:

Red

Clarity:

Eye clean

Origin:

Zagi Mountain, Pakistan

Treatment:

None (natural)

Price:

SOLD

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Genthelvite-001

A very rare collector's gem from Pakistan. This gem is small but has great color. A very rare gem to add to any collection.


 

I love Sarah