Transactions . age 255. § Fluorspar-deposits of Southern Illinois, by Mr. S. F. Emmons, Trans-actions of the American Institute of Mining Engineers, 1892, vol. xxi., page 31. |[ American Gems and Precious Stones, by Mr. G. V. Kunz, United StalesGeological Survey : Mineral Resources of the United States, 1882, page 497. 206 OCCURRENCE AND COMMERCIAL USES OF FLUORSPAR. Mr. J. H. Cardin also states that Tradition says that it was inthis chamber [the crystal chamber] that the inhabitants tookrefuge when in fear of the Young Pretender and his adherents,in the year 1745, and either to pass away the
Transactions . age 255. § Fluorspar-deposits of Southern Illinois, by Mr. S. F. Emmons, Trans-actions of the American Institute of Mining Engineers, 1892, vol. xxi., page 31. |[ American Gems and Precious Stones, by Mr. G. V. Kunz, United StalesGeological Survey : Mineral Resources of the United States, 1882, page 497. 206 OCCURRENCE AND COMMERCIAL USES OF FLUORSPAR. Mr. J. H. Cardin also states that Tradition says that it was inthis chamber [the crystal chamber] that the inhabitants tookrefuge when in fear of the Young Pretender and his adherents,in the year 1745, and either to pass away the time or to frightenany intruders, they carved out from the solid spar a figure inthe shape of a lion.* Colour, etc.—The term fluorescence was first applied toa physical property observed in this mineral, namely, that whenexposed to light fluorspar becomes fluorescent—a peculiar colourappearance akin to phosphorescence. Fluorspar, when crackedalong the cleavage-planes or when possessing edge-fractures, has,. Fig. I. — Vases Made from Derbyshire Blue John. under certain light, a silvery-white appearance, but one mayget all the colours of the spectrum or rainbow—red, orange,yellow, green, blue, indigo, and violet. This colour-picture isone of the prettiest exhibited by this mineral. If the fracturesare crossed, a mosaic jumble of rainbow colours is the result. Afracture through the point or solid angle of a coloured cuberenders the point from the crack white, the other part retainingits original green or purple tint. * Visitors New Guide to Matlock, by Mr. J. H. Cardin, 1873, page 51. OCCURRENCE AND COMMERCIAL USES OF FLUORSPAR. 207 This mineral possesses quite a suite of colours. One mayhave a colourless crystal of fluorspar, then one with a faintpurple shade or with all the shades or tints from pinkish to deepviolet or blue. Pink or rose-coloured fluorspar is rare, but allshades of purple to deep violet are common in the colouring is seen in specimen
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