Fluorite - Cave-in-Rock, Illinois USA
World Minerals


Fluorite from Cave-in-Rock, Illinois USA


    This beautiful translucent specimen of Fluorite comes from Cave-in-Rock, Illinois, USA and shows a deep purple under good light.

    Fluorite is an important industrial mineral composed of calcium and fluorine (CaF2) and is also known as Fluorspar. It is very easy to identify as it is the only common mineral that has four directions of perfect cleavage, often breaking into pieces with the shape of an octahedron. Crystal twinning is common and adds complexity to the observed crystal habits.

    Fluorite normally glows a blue-violet colour under short-wave UV (ultraviolet) and long-wave UV light. Some specimens can glow a cream or white colour while many specimens do not fluoresce at all. Another interesting point is that the term “fluorescence” came from George Gabriel Stokes in 1852 after illuminating a specimen with light.

    I acquired this specimen from Greg at Blue Gems Minerals at the August 2016 Sydney Crystal Show.

    Specimen Details

    Chemical Formula: CaF2

    Collection ID #: JG0012

    Colour: This specimen is a nice deep purple when viewed in good light.
    Fluorite comes in various other colours, including colourless, green, white, blue, pink, red, yellow, orange, brown, gray and black. It can also be multicoloured and banded.

    Hardness: 4

    Acquisition Date: 6th August 2016

    Crystal System: Isometric

    Lustre: Vitreous

    Dimensions: 76mm x 68mm x 82mm

    Weight: 392g

    Locale: Cave-in-Rock, Illinois, USA

    Rarity of Mineral

    Very Common

    Did you know!?
    The term fluorescence was derived from the mineral name Fluorite. Generally it fluoresces blue but other fluorescent colours include red, green, yellow, white and purple. Some will even demonstrate phosphorescence.