Cebollite was named after the Cebolla Creek in Colorado, USA, where the mineral was first located.
Chemical Formula – Ca5Al2Si3O12(OH)4
Properties of Cebollite
The following are the key properties of cebollite:
- Space group: n.d. i.e. the symmetry group of a configuration in three-dimensional space
- Z = n.d.
- Point group: n.d. i.e. how the orientation of a crystal can be changed without altering the position of its atoms
- As compact masses of minute radiating fibers
- X-ray powder pattern: 2.73 (100), 2.88 (90), 2.59 (70), 1.62 (60), 3.01 (50), 2.90 (40), 2.45 (40)
- Optical class: Biaxial (+)
- Dispersion: r > v, weak
- α = 1.592-1.595; β = 1.597-1.60; γ = 1.628-1.630
- 2V(meas.) =~58°
||Bulk density (electron density) = 2.97 g/cm3
note: Specific gravity of cebollite =2.96 g/cm3
||PE Cebollite = 4.90 barns/electron
U=PE Cebollite x ρ electron density= 14.55 barns/cm3
||Fermion index = 0.0072311321
Boson index = 0.9927688679
||Cebollite is not radioactive
How to Identify Cebollite
Cebollite can be identified in the field by its color variations such as greenish grey, white, and light brown. It is sometimes colorless. Its sub-translucent to opaque form has no cleavage. This mineral has a vitreous – dull luster with a white streak. The density of cebollite is 2.96 g/cm3 with a hardness of 5 on the Mohs scale – approximate to apatite, a pale green to purple mineral consisting of calcium phosphate with chlorine and fluorine. It is non-fluorescent as well as non-magnetic.
Occurrence of Cebollite and Useful Mineral Association
Cebollite occurs as an alteration product of melilite in a carbonatite; along a diabase-chalk contact; in zeolitized plagioclase-rich gneiss, amphibolite, and basalt xenoliths; and as a late-stage primary igneous mineral. It is often associated with minerals such as melilite, diopside, natrolite, phlogopite, vesuvianite, garnet, and calcite.
Sources and Further Reading
This article was updated on 3rd February, 2020.