This semi-transparent piece of fluorite has a deep purple color with a glassy surface, as shown in the lower right corner of the first image. The photo highlights the stepped growth of the cubic crystals.


Detail view.


Side 1

Side 2

Approximate Photo Location (Side 1)


Magnification: ~2.2X

Field of view: ~7/16” x 5/8“ (11.0mm x 16.5mm)

Images in focus stack: 109


The image below shows the impact of the lighting on the piece. On the left is the view through the camera’s viewfinder, and on the right a single frame as captured by camera. The flash was positioned so that most of the light reflected off the face, emphasizing the surface details/depth at the cost of reproducing the color.

Fluorite ranges from transparent to translucent and is found in purple, green, yellow, blue, pink, colorless, and other varieties (1, 2, 3). In some cases it also glows under short- and long-wave ultraviolet light (the word “fluorescence” was coined after this phenomenon in the mid-19th century by George Gabriel Stokes)(3, 4). Industrially, fluorspar (concentrates of fluorite) is commonly used in the manufacture of hydrofluoric acid and steel/aluminum (5, 7). In steel production, it serves as a flux that lowers the melting point of the iron ore, helps remove impurities, and improves the fluidity of the slag (4, 8). (Slag is a by-product that is removed when the iron is separated from the ore.) The use of fluorspar as a flux was known and recorded in the 16th century by Georgius Agricola (5, 6). He called the mineral “fluores,” as derived from the Latin word “fluere,” which means to flow (3, 5, 6).


1. Fluorite: Illinois’ State mineral. (n.d.). Retrieved from the Illinois State Geological Survey.

2. Jones, B. (n.d.). Introduction to fluorite. Retrieved from the Tidewater Gem & Mineral Society.

3. The University of Minnesota. (n.d.). Fluorite. Retrieved from the U of M Department of Geology.

4. King, H. M. (n.d.). Fluorite (also known as fluorspar). Retrieved from Geology.com.

5. US Geological Survey. (2010). Mineral resource of the month: Fluorspar. Retrieved from USGS.

6. Reger, L., Goode, S., & Ball, D. W. (2009). Chemistry: Principles and practice. Retrieved from Google Books.

7. Bide, T., Gunn, G., Brown, T. & Rayner, D. (2011). Fluorspar. Retrieved from the British Geological Survey.

8. CRM_InnoNet (Critical Raw Materials Innovation Network). 4. Fluorspar. Retrieved from CRM_InnoNet.



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