Stone of the Week - Fluorite

Sunday, March 2, 2008
Fluorite, also known as Fluorspar, is made up of calcium fluoride (CaF2). The name fluorite is derived from the Latin fluo, meaning "flow", because it is slightly dissolvable in water. Fluorite belongs to the Isometric crystal system, otherwise known as the cubic crystal system. This means that its most basic form (properly called a ‘unit cell’) is a cubic shape; hence the crystals are commonly cubic.


Fluorite can be found in a vareity of beautiful colors including blue, pink, blue-green, and purple.



Fluorite can occur as a variety of colors, including green, blue, purple, pink, yellow, and white. These colors can occur as angular banding, commonly referred to as ‘chevron’ banding. A neat property of fluorite is that it is fluorescent – in fact this is where the term fluorescent came from. When held under UV light, the electrons inside the fluorite become ‘excited’ resulting in their energy level increasing – when they come back down from this ‘excited state’ light is released. Usually in fluorite this will be blue, but other colors are known to occur.

Fluorite can often be found as cubic crystals (left) and a bit more rarely this gorgeous chevron banding (right).



In the United States, the state of Illinois is the most abundant location for fluorite, and is the official mineral of Illinois. This area is often called the ‘fluorspar district’, and was mined until 1995 when the last mine closed – now it’s a popular location for rockhounds to collect specimens. Another famous locale for fluorite is in Castleton in Derbyshire, England. Here there is a unique blue and purple fluorite called ‘Blue John’ and is used for ornamental stone. Fluorite is a popular stone for jewelry work, though care must be taken as it is a ‘soft’ stone with a hardness of 4 on the Mohs hardness scale.

Fluorite makes for a beautiful stone to use in jewelry and ornamental work.


If there's a stone you would like to know more about - drop me a line! Have a mystery stone? Feel free to post a comment about it, including a link to a picture, and it could be featured on this blog!


Fluorite Facts:
Chemical composition: CaF2
Crystal System: Isometric
Color: blue, green, purple, pink, white/clear, yellow, brown, red, black
Habit: Crystals, Granular, Massive
Fracture: Uneven, Conchoidal
Cleavage: Perfect
Luster: Vitreous
Transparency: Transparent
Hardness: 4
Specific Gravity: 3.3
Streak: White
Occurrence: Worldwide, but most commonly in the US and UK
Other: Fluorescence, some specimens may exhibit thermoluminescence


References

Rocks, Minerals, & Fossils of the World by C. Pellant and R. Phillips. Published 1990 by Little, Brown and Co. ISBN: 0316697966

Wikipedia – Fluorite. http://en.wikipedia.org/wiki/Fluorite

1 comments:

Little Brown Sparrow said...

HI, just found your blog today and I must say it's lovely, and looks to be quite handy for me, as I find crystal jewellery on my thrift hunting all the time and have no idea what it is!

I found this heart just last week: http://tiny.cc/hI4U9 and was wondering if you could tell me what it's made of. It's a murky tea colour and has short straight fissures (right word?) inside that look like bristles.

Thank you so much!