Cavansite
Current inventory:  2 gems
 

  
Cavansite is named for the Calcium, Vanadium, and Silicon in its composition.

Discovered in 1967;   IMA status:  Valid (IMA approved 1973)

Chemistry

Chemical Formula:

CaV⁵⁺Si₄O₁₁·4(H₂O)

Hydrated Calcium Vanadium Silicate

Molecular Weight:

451.42 gm

Composition:

Calcium

8.88 %

Ca

12.42 %

CaO

Vanadium

11.28 %

V

20.15 %

V₂O₅

Silicon

24.89 %

Si

53.24 %

SiO₂

Hydrogen

1.79 %

H

15.96 %

H₂O

Oxygen

53.16 %

O

100.00 %

101.77 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/H.36-10

Nickel-Strunz 10th Ed. ID:

9.EA.50

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings

Related to:

Dimorphous with Pentagonite. Ishida et al. (2009) suggest that Cavansite is a low-temperature form and Pentagonite a high-temperature from.

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Orthorhombic - Dipyramidal

Crystal Habit:

As prismatic crystals, to 1 mm, elongated || [001]; dominant forms {110} and {101}; as spherulitic rosettes, to 5 mm.

Twinning:

None

Physical Properties

Cleavage:

Good on {010}

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

3.0 - 4.0

Density:

2.21 - 2.31 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Brilliant Sky Blue, Dark Blue, Greenish Blue

Transparency:

Subtransparent to Transparent

Luster:

Vitreous

Refractive Index:

1.542 - 1.551  Biaxial ( + )

Birefringence:

0.009

Dispersion:

Weak to Extreme; r < v

Pleochroism:

Pronounced; X = colorless; Y = blue; Z = colorless

Occurances

Geological Setting:

In a brown tuff partly filling a fault fissure (Lake Owyhee State Park, Oregon, USA); in a vesicular basalt and red tuff breccia, as cavity fillings and in calcite veinlets (Chapman quarry, Oregon, USA); in pores of altered basalt breccia and tuffaceous andesite (Poona district, India).

Common Associations:

Pentagonite, Calcite, Heulandite, Stilbite, Analcime, Apophyllite, Thomsonite, Copper (Oregon, USA); Stilbite, Calcite, Heulandite, Mordenite, Chalcocite (India).

Common Impurities:

None

Type Locality:

Owyhee Dam, Lake Owyhee State Park, Malheur Co., Oregon, USA

Year Discovered:

1967 (IMA approved 1973)

View mineral photos:

Cavansite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Cavansite is a rare mineral with crystals that are always far too small for faceting and are usually too small even for cabochons. It is mostly collected as mineral specimens for its beautiful blue color displays of radial crystals and spherulitic rosettes.

Cavansite was originally discovered near Owyhee Dam, Lake Owyhee State Park, Malheur County, Oregon, USA and later at the Chapman quarry, Columbia County, Oregon, USA. Cavansite has recently found as remarkable specimens from quarries around Wagholi, Poona district, Maharashtra, India.
 

  
Cavansite gems for sale: