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

           


Hexagonite  (variety of Tremolite)
Current inventory:  1 gem
 

Hexagonite

Chemistry:  Ca2Mg5(Si8O22)(OH)2

Discovered in 1789 (Tremolite);   IMA status: Hexagonite: Not Valid; Tremolite: Valid
Hexagonite was named for being a hexagonal form of Tremolite but was later shown to be monoclinic. The name Hexagonite has been rejected by the IMA. Tremolite was named by J.G.A.
Höpfner for the Tremola Valley (Val Tremola), Central St. Gotthard Massif, Switzerland where the type material was originally thought to be found.

 

Classification

   

   

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/F.10-10

Nickel-Strunz 10th Ed. ID:

9.DE.10

 

9 : SILICATES (Germanates)
D : Inosilicates
E : Inosilicates with 2-periodic double chains, Si
4O11; Clinoamphiboles

Related to:

Amphibole group;
Forms a series with Actinolite;
Forms a series with Ferro-Actinolite;
Forms a series with Parvo-manganotremolite

 

 

Crystal Data

   

   

Crystallography:

Monoclinic - Prismatic

Crystal Habit:

Elongated, stout prismatic, bladed crystals, fibrous, granula, columnar aggregates

Twinning:

Tremolite: Simple or multiple: common parallel to [100], rarely parallel to [001]

 

 

Physical Properties

   

 

Cleavage:

[110] Perfect , [010] Distinct

Fracture:

Uneven

Tenacity:

Brittle

Hardness (Mohs):

5.0 - 6.0

Density:

2.90 - 3.20 (g/cm3)

Luminescence:

Orange, medium pink to pinkish red fluorescence in LW and SW UV

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Pale Lilac, deep Rose, deep Red-Violet, Purplish

Transparency:

Transparent, Translucent

Luster:

Vitreous

Refractive Index:

1.599 - 1.637  Biaxial ( - )

Birefringence:

0.019 - 0.028

Dispersion:

Weak; r < v

Pleochroism:

Bluish-Red/deep Rose/deep Red-Violet

 

 

Occurances

   

   

Geological Setting:

Contact metamorphism of Ca-Mg siliceous sediments, regional greenschist metamorphism of ultramafic rocks or magnesium carbonate rocks.

Common Associations:

Calcite, Dolomite, Calcian Garnet, Wollastonite, Talc, Diopside, Forsterite, Cummingtonite, Magnesio-Cummingtonite, Riebeckite, Winchite

Type Locality:

Edwards, Balmat-Edwards Zinc District, St Lawrence County, New York, USA

Year Discovered:

1789 (Tremolite)

View mineral photos:

Hexagonite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org (Hexagonite)
Mindat.org (Tremolite)
Webmineral.com (Tremolite)

 

 


Hexagonite is the rarest of the gem varieties of Tremolite. It is the Manganoan variety of Tremolite distinguished by its pale lilac to purplish color. Tremolite is a member of the Amphibol mineral group that also includes Actinolite, Jade and Nephrite.

Hexagonite is found only in New York, USA in four locations: Edwards, Fowler and Talcville in St. Lawrence County; and Harrisville in Lewis County.
 

  
Hexagonite gems for sale:

Hexagonite-001

Gem:

Hexagonite

Stock #:

HEX-001

Weight:

0.1460 ct

Size:

4.16 x 3.04 x 1.83 mm

Shape:

Oval

Color:

Pink

Clarity:

SI2 - I2

Origin:

Edwards, New York, USA

Treatment:

None (natural)

Price:

SOLD (but we have others)

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

Hexagonite-001

A very rare collector's gem from Edwards, New York, USA.


 

I love Sarah