Fluorite
Calcium fluoride in every colour, the mineral that named fluorescence.
- Family
- Fluorite
- Formula
- CaF₂
- Mohs
- 4
- System
- Cubic
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Science
Fluorite forms perfect cubes and octahedra in hydrothermal veins and is the main source of fluorine. Its colours come from trace rare earths and radiation defects, and many specimens glow blue under ultraviolet light: George Stokes named the phenomenon 'fluorescence' after it in 1852. It cleaves perfectly into octahedra.
- Mineral
- Fluorite
- Formula
- CaF₂
- Crystal system
- Cubic
- Mohs hardness
- 4
- Specific gravity
- 3.18
- Refractive index
- 1.434
- Lustre
- Vitreous
- Colours
- Purple, Green, Blue, Yellow, Banded
Composition
CaF₂. Made of Calcium, Fluorine, with trace Yttrium, Cerium responsible for colour.
Origin
- China
- Mexico
- South Africa
- Mongolia
- United KingdomBlue John, Derbyshire; Rogerley
- United StatesIllinois, historic
- SpainAsturias
Filled dots are primary sources
Rarity
An industrial mineral mined by the megatonne. Fine crystals from Rogerley or Asturias, and Blue John, are the collectable end.
- 1 Abundant
- 2 Common
- 3 Uncommon
- 4 Rare
- 5 Exceptional
Hardness
Fluorite sits at 4 on the Mohs scale. A steel knife will scratch it; it suits pendants and display more than rings.
Energy
Associations from crystal-healing tradition, recorded here as folklore. They are not medical claims.
Chakras
- Third Eye
- Heart
Element
- Air
Zodiac
- Pisces
- Capricorn
Planets
- Neptune
- Mercury
Properties
- Focus
- Mental order
- Learning
- Decision
Lore
Romans carved murrhine vases from Blue John-like fluorite that were worth a senator's fortune; Derbyshire Blue John has been turned into bowls since the 1700s. The name is from fluere, to flow, since it is used as a flux in smelting.
Modern practice makes it the study stone: order in the mind, following the geometry of its crystals.
- FluorescenceNamed after fluorite in 1852.
- LensesFluorite glass corrects colour in camera and telescope optics.