|
Click on a
letter above to view the list of gems. |
|
| Chemistry:
(Ca,Na)2-3Al3(Al,Si)2Si13O36•12H2O [Hydrated Sodium Calcium Aluminum Silicate] | Discovered
in 1822;
IMA
status: Valid (pre-IMA; Grandfathered). Heulandite
is named after John Henry Heuland (1778-1856), a British mineral collector and dealer. |
|
Classification
|
|
|
Mineral
Classification: |
Silicates |
Strunz 8th
Ed. ID:
|
8/J.23-10
|
Nickel-Strunz 10th
Ed. ID:
|
9.GE.05 |
|
9 : SILICATES (Germanates) G : Tektosilicates with zeolitic
H2O; zeolite family E : Chains of T10O20
Tetrahedra
|
Related
to: |
Zeolite Group. Heulandite - Barium
- Brewsterite Series. Clinoptilolite-Ca - Heulandite-Ca
Series. The calcium analogue of Heulandite-Ba, Heulandite-K,
Heulandite-Na and Heulandite-Sr.
|
|
|
Crystal
Data
|
|
|
Crystallography:
|
Monoclinic
- Prismatic
|
Crystal
Habit:
|
Crystals
commonly tabular and elongated, widest at the center,
hence called "coffin-shaped," to 12 cm; also
granular to massive.
|
Twinning:
|
With
[100] as twin and contact plane.
|
|
|
Physical
Properties
|
|
|
Cleavage: |
[010]
Perfect
|
Fracture: |
Sub-Conchoidal
to Irregular/Uneven
|
Tenacity:
|
Brittle
|
Hardness
(Mohs): |
3.5
- 4.0
|
Density:
|
2.10
- 2.20 (g/cm3)
|
Luminescence:
|
None |
Radioactivity:
|
Barely
Detectable;
GRapi = 8.68 (Gamma Ray American Petroleum Institute Units)
|
|
|
Optical
Properties
|
|
|
Color: |
Colorless,
White, Gray, Green, Pink, Yellow, Red, Brown and Black
|
Transparency: |
Transparent,
but most often Translucent to Sub-Translucent |
Luster: |
Vitreous,
Pearly on cleavages |
Refractive
Index: |
1.491
- 1.512 Biaxial ( + )
|
Birefringence: |
0.0030
- 0.0110
|
Dispersion: |
Distinct,
Crossed; r > v
|
Pleochroism: |
None |
|
|
Occurances
|
|
|
Geological
Setting: |
In
cavities in basalts; in highly weathered andesites and
diabases; as a devitrification product of volcanic glasses
and tuffs. |
Common
Associations: |
Apophyllite,
Calcite, Datolite, Zeolites |
Type
Locality: |
Linópolis, Divino das Laranjeiras, Doce valley, Minas
Gerais, Southeast Region, Brazil |
Year
Discovered: |
1822
|
View
mineral photos: |
Heulandite
Mineral Photos and Locations |
|
|
More
Information
|
|
|
|
Mindat.org Webmineral.com |
|
|
Heulandite
is one
of the members of the Zeolite
Group of minerals that includes
many minerals and these gem-type minerals: Analcime,
Chabazite, Heulandite,
Mordenite,
Natrolite,
Pollucite,
Scolecite, Stilbite,
Thomsonite and Yugawaralite. Heulandite
is one of the most common and one of the most well known members of
the Zeolite Group. It forms complex and unique crystals with a nice pearly luster
and beautiful shades of pinks, greens and yellows. Crystals
are rarely transparent, but do have a nice translucency
to them.
There
are many locations for Heulandite but some of the best
specimens come from Linópolis, Divino das Laranjeiras, Doce valley, Minas
Gerais, Southeast Region, Brazil; Nasik and Pune (Poonah) Districts, Maharashtra, India;
Drio le Pale, Buffaure Group, Fassa Valley, Trento
Province, Trentino-Alto Adige, Italy; Rats Nest Claim, Challis, Custer County, Idaho, USA.
|
Heulandite
gems for sale:
We
have not photographed our Heulandite
gems. Please
check back soon.
|
|