Cavansite

Last updated
Cavansite
Cavansite-121680.jpg
Cavansite on heulandite
General
Category Phyllosilicate minerals
Formula Ca(VO)Si 4 O 10·4(H2O)
IMA symbol Cav [1]
Crystal system Orthorhombic
Crystal class Dipyramidal (mmm)
H–M Symbol: (2/m 2/m 2/m)
Space group Pcmn
Unit cell a = 9.792(2) Å,
b = 13.644(3) Å,
c = 9.629(2) Å; Z = 4
Identification
ColorBrilliant sky-blue to greenish blue
Crystal habit Radiating acicular prismatic crystals commonly as spherulitic rosettes
Cleavage Good on {010}
Tenacity Brittle
Mohs scale hardness3 - 4
Luster Vitreous, pearly
Streak Bluish-white
Diaphaneity Transparent
Specific gravity 2.25 - 2.33
Optical propertiesBiaxial (+)
Refractive index nα = 1.542(2) nβ = 1.544(2) nγ = 1.551(2)
Birefringence δ = 0.009
Pleochroism Visible: X=Z= colorless Y= blue
2V angle Measured: 52°
References [2] [3] [4] [5]

Cavansite, named for its chemical composition of calcium vanadium silicate, is a deep blue hydrous calcium vanadium phyllosilicate mineral, occurring as a secondary mineral in basaltic and andesitic rocks along with a variety of zeolite minerals. Its blue coloring comes from vanadium, a metal ion. [6] Discovered in 1967 in Malheur County, Oregon, cavansite is a relatively rare mineral. It is polymorphic with the even rarer mineral, pentagonite. It is most frequently found in Pune, India, and in the Deccan Traps, a large igneous province.

Contents

Uses of cavansite

Although cavansite contains vanadium, and could thus be a possible ore source for the element, it is not generally considered an ore mineral. However, because of its rich color and relative rarity, cavansite is a sought-after collector's mineral.

Associated minerals

Notes for identification

Stalactitic cavansite, 3.6 x 2.1 x 1.8 cm, Wagholi, Pune District, Maharashtra, India Cavansite-indi-12a.jpg
Stalactitic cavansite, 3.6 x 2.1 x 1.8 cm, Wagholi, Pune District, Maharashtra, India

Cavansite is a distinctive mineral. It tends to form crystal aggregates, generally in the form of balls, up to a couple centimeters in size. Sometimes, the balls are coarse enough to resolve individual crystals. Rarely, cavansite forms bowtie-shaped aggregates. The color of cavansite is distinctive, almost always a rich, bright blue. The color is the same as its dimorph, pentagonite, but the latter is generally much more spikey with bladed crystals. Finally, the associated minerals aid identification, as cavansite is frequently found atop a matrix of zeolites or apophyllites.

References

  1. ↑ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi: 10.1180/mgm.2021.43 . S2CID   235729616.
  2. ↑ Mineralienatlas
  3. ↑ Handbook of Mineralogy
  4. ↑ Mindat
  5. ↑ Cavansite Mineral Data, Mineralogy Database webmineral.com
  6. ↑ "Minerals Colored by Metal Ions". minerals.gps.caltech.edu. Retrieved 2023-02-28.

Further reading

Commons-logo.svg Media related to Cavansite at Wikimedia Commons

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.