Abstract

Phosphorescence of calcite and fluorite, exposed for a few minutes to 2537° ultraviolet light from a low-pressure cold quartz mercury vapor lamp, persisted for 18 years. Emission was detected by placing the phosphorescing minerals on black-and-white and Kodachrome film, to obtain “phosphorographs” of the glowing areas. The rate of emission depends on temperature; the color of the phosphorescence has not changed; these confirm the results of other tests that prove that radioactivity is not involved. The patterns of growth of a crystal, and changes of its environment during formation, are clearly shown by the variegated colors in its phosphorograph.

© 1964 Optical Society of America

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References

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  1. H. E. Millson and H. E. Millson, J. Opt. Soc. Am. 40, 430 (1950).
    [Crossref]

1950 (1)

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Figures (2)

F. 1
F. 1

Phosphorograph of calcite from Chisos Mountains, Texas. Specimen exposed to ultraviolet rays for 1 min and kept in dark for 18 years, at end of which time this phosphorograph was produced. The specimen was in contact with the film for 5159 h.

F. 2
F. 2

Phosphorograph of fluorite crystal from Cumberland, England, showing crystal growth. Phosphorograph taken 153 h after a 1-min exposure to ultraviolet rays. The specimen was in contact with the film for 48 h.