Halides · Sourced PROFILE
Fluorite
CaF₂
A colourful calcium fluoride mineral notable for perfect cleavage and frequent fluorescence.
AT A GLANCE
- Formula
- CaF₂
- Crystal system
- Cubic
- Space group
- Fm̅3m
- Mohs hardness
- 4
- Density
- 3.175–3.184 g/cm³
- Optical character
- Isotropic
CRYSTALLOGRAPHY
Crystal form & structure
Cubes and octahedra are common, often intergrown; penetration twins occur. Massive, granular, botryoidal, or fibrous material is also known.
HAND-SAMPLE PROPERTIES
Physical properties
- Cleavage
- Perfect octahedral cleavage on {111}
- Fracture
- Subconchoidal to uneven
- Tenacity
- Brittle
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Observed colours
- Colourless, purple, green, yellow, blue, pink, brown, or nearly black; colour zoning is common
LIGHT & OPTICS
Optical properties
- Optical class
- Isotropic
- Refractive index
- n 1.433–1.448
- Fluorescence & electrical behaviour
- Frequently fluorescent, but colour and intensity vary widely with trace activators, defects, and locality; fluorescence is not guaranteed.
GEOLOGICAL SETTING
Formation
Often forms in hydrothermal veins and cavities, sometimes with metallic ores.
MINERAL COMPANY
Common associations
Calcite, quartz, barite, galena, sphalerite, pyrite, dolomite, and other hydrothermal minerals
FIELD NOTES
How to identify it
Hardness 4, perfect four-direction octahedral cleavage, cubic habit, and isotropic optics are diagnostic. Cleavage fragments often resemble octahedra even when the original crystal was cubic.
NAME & HISTORY
Where the name comes from
From Latin fluere, to flow, because fluorite was used as a metallurgical flux.
SCIENTIFIC SOURCE
Handbook of Mineralogy — Fluorite
External reference; factual profile paraphrased and attributed. Copyright remains with the publisher.
PROVENANCE
Documented occurrences
Konchoch area, Ayni District · The USGS reports fluorite in the Konchoch and Shakhkon polymetallic deposits. This is a deposit record, not permission or guidance for collecting.
Sourced · District precisionU.S. Geological Survey: Mineral Industry of Tajikistan in 2022