Natural fluorescent minerals can glow from exposure to sunlight.
the verdict
CONTESTED
contested - the weight sits with the supporting side
refutedsupported
the weight of evidence
3 sources for · 0 against
AS REPORTEDno primary record reached; this is what the reporting says
Source evidence mentions phosphorescent minerals like diamonds and fluorescent light from X-rays, but does not sufficiently establish that natural fluorescent minerals glow from exposure to sunlight.
phosphorescent minerals such as diamonds. First, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light
Folktales about luminous gemstones are an almost worldwide motif in mythology and history among Asian, European, African, and American cultures. Some stories about light-emitting gems may have been based on luminescent and phosphorescent minerals such as diamonds.
First, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light, friction, or heat. Note that the following discussion will omit modern techniques such as X-rays and ultraviolet light that are too recent to have influenced folklore about luminous gems. Luminescence is spontaneous emission of light by a substance not resulting from heat, as distinguished from incandescence, which is light emitted by a substance as a result of heating. Luminescence is caused by the absorption of energy that is released in small amounts. When the energy comes from light or other electromagnetic radiation, it is referred to as photoluminescence; which is divisible between fluorescence when the glow ceases immediately with the excitation and phosphorescence when the glow continues beyond the period of excitation. Two types of luminescent phenomena are relevant to crystalline materials. Triboluminescence generates light through the breaking of chemical bonds in a material when it is rubbed, pulled apart, scratched, or crushed. Thermoluminescence re-emits previously absorbed electromagnetic radiation upon being heated (e.g., thermoluminescence dating).
The American geologist Sydney Hobart Ball, who wrote an article on "Luminous Gems, Mythical and Real", outlined the history of discoveries about luminescent and phosphorescent minerals. Most diamonds are triboluminescent if rubbed with a cloth, and a few are photoluminescent after exposure to direct sunlight. Both diamonds and white topaz may phosphoresce if heated be
Folktales about luminous gemstones are an almost worldwide motif in mythology and history among Asian, European, African, and American cultures. Some stories about light-emitting gems may have been based on luminescent and phosphorescent minerals such as diamonds. == Mineralogical luminosity == First, it will be useful to introduce some mineralogical terminology for gemstones that can glow when exposed to light, friction, or heat. Note that the following discussion will omit modern techniques such as X-rays and ultraviolet light that are too recent to have influenced folklore about luminous gems.
Triboluminescence generates light through the breaking of chemical bonds in a material when it is rubbed, pulled apart, scratched, or crushed. Thermoluminescence re-emits previously absorbed electromagnetic radiation upon being heated (e.g., thermoluminescence dating). The American geologist Sydney Hobart Ball, who wrote an article on "Luminous Gems, Mythical and Real", outlined the history of discoveries about luminescent and phosphorescent minerals. Most diamonds are triboluminescent if rubbed with a cloth, and a few are photoluminescent after exposure to direct sunlight. Both diamonds and white topaz may phosphoresce if heated below red heat.
In 1735, the French chemist Charles François de Cisternay du Fay determined that lapis lazuli, emerald, and aquamarine were luminescent. Josiah Wedgwood, in 1792, found phosphoresce from rubbing together two pieces of quartz or of agate, and wrote that the ruby gives "a beautiful red light of short continuance." Edmond Becquerel reported in 1861 that ruby fluoresces better than sapphire, red feldspar fluoresces, and crushed orthoclase will flame. In 1833, David Brewster discovered the fluorescence of the mineral fluorite or fluorspar.
Chlorophane is unusual for combining the properties of thermoluminescence, triboluminescence, phosphorescence, and fluorescence; it will emit visible spectrum light when rubbed, or exposed to light or heat, and can continue emitting for a long period of time. Among the gravels of the Irtysh River, near Krasnoyarsk, Russia, the German mineralogist Gustav Rose recorded seeing chlorophane pebbles that shone with brilliancy all night long, merely from exposure to the sun's heat.
Schafer proposes that the phosphorescent "emeralds" of classical antiquity, such as the brilliantly shining green eyes of the marble lion on the tomb of King Hermias of Atarneus (d. 341 BCE) on Cyprus, were fluorite, even though the Hellenistic alchemists had methods, "seemingly magical, of making night-shining gems by the application of phosphorescent paints to stones", the most famous being their "emeralds" and "carbuncles". The names of some
The French chemist Marcellin Berthelot (1888) discovered an early Greek alchemical text "from the sanctuary of the temple" that says the Egyptians produced "the carbuncle that shines in the night" from certain phosphorescent parts ("the bile") of marine animals, and when properly prepared these precious gems would glow so brightly at night "that anyone owning such a stone could read or write by its light as well as he could by daylight". === Gem mining legends === Second, there are stories about miners finding luminous gems at night and extracting them by day. One notable exception is Pliny's c.
Das älteste Dokument zur Chinesischen Kunstgeschichte Tianwen. T'ien-wen; die 'Himmelsfragen' des K'üh Yüan [The oldest document on Chinese art history Tianwen. T'ien-wen; the 'Heavenly Questions' of K'üh Yüan] (in German). Leipzig, Germany: Verlag Asia Major – via Arhive.org. De Ment, Jack (1949), Handbook of Fluorescent Gems and Minerals – An Exposition and Catalog of the Fluorescent and Phosphorescent Gems and Minerals, Including the Use of Ultraviolet Light in the Earth Sciences, Mineralogist Publishing Company. Eberhard, Wolfram (1968), The Local Cultures of South and East China, Alide Eberhard, tr. Lokalkulturen im alten China, 1943, E.J. Brill.
It was noticed that an exhausted bulb which is emitting X-rays under the influence of electrical discharges is always aglow with a peculiar greenish-yellow light which is commonly known as fluorescent light.
Now it had long been known that there are some natural substances, notably the mineral uranium and its compounds, which possess a similar property of emitting this yellowish-green light not only when they are in a vacuum tube through which electrical discharges are passing, but also when they are exposed to the invisible radiation from the sun, that is, to the so-called actinic or ultra-violet rays which are chiefly responsible for the effects which sunlight produces upon photographic plates.
It accordingly very naturally occurred to some scientists that the X-rays might perhaps be due to this fluorescent light which came from a vacuum bulb, rather than to any immediate influence of the electrical discharge, and, if so, that they ought to be emitted not simply by a vacuum tube, but also by uranium when exposed to sunlight. It was in 1896, within a year of the discovery of X-rays, that Henri Becquerel, the fourth illustrious possessor of that illustrious name, devised some experiments to test this inference.
His method  ​ was to expose uranium to strong sunlight for a long time, and then to notice whether a photographic plate, which was wrapped up carefully in perfectly opaque paper and placed beneath the uranium, received any impression from it. He found that it did; but he further found that the exposure of the uranium to sunlight was altogether unnecessary; that the uranium itself in a perfectly dark room would affect, in the course of ten or twenty days, a photographic plate from which it was separated both by opaque black paper and by a thin sheet of metal.
In fact he obtained in this way a radiograph of a metallic object similar in all respects to the pictures which Röntgen had obtained with X-rays. This showed, in the first place, that the fluorescent light had nothing whatever to do with the production of the photograph, but it showed also something much more important than this, namely, that the mineral uranium is all the time spontaneously emitting rays of some sort, which are capable of penetrating opaque objects in just the way the X-rays do.
This discovery, which has been one of the most fruitful in the history of science, is immediately due to the accident of a few cloudy days in Paris, during which Becquerel, since he could not expose his uranium to sunlight, set away his plate with the uranium on the top of it, to wait for fair weather. When the fair weather returned and he was ready to continue his experiments, it fortunately occurred to him that it might be worth while to develop the plate upon which the uranium had rested to see if anything had happened to it. The discovery of radio-activity was the result.
If A and B are two diaphragms, in the middle of which are two horizontal slits, then, when an induction coil is connected to the points marked + and — and set into operation, a small spot of greenish-yellow light will appear on the glass at P, just as though some sort of rays were emitted in straight lines from C, and, passing through the two openings O, fell upon the point P. There are a great many substances which, if placed anywhere in the line OP so that these cathode rays from C can strike upon them, will light up with a   ​ characteristic glow. For example, if a screen coated with, zinc sulphide is placed within a discharge tube in the manner shown in Fig.
But no amount of reasoning of the sort thus far given will be found half as convincing to the ordinary mind as the sight of a bit of radium at work. Radium itself, in the dark, glows with a light which resembles that of a glowworm, and when placed near certain substances like willemite (zinc silicate) or zinc sulphide, it causes them to light up with a glow which is more or less brilliant according to the amount of the radium at hand. Last spring Sir William Crookes first exhibited the following most beautiful and wonderful experiment at the soirée of the Royal Society in London.
A small bit of radium is placed about a millimeter above a zinc sulphide screen, and the latter is then viewed through a microscope of from ten to twenty diameters magnification. The continuous soft glow of the screen, which is all that one sees with the naked eye, is resolved by the microscope into a thousand tiny flashes of light. It is as though one were viewing a swamp full of fire flies, or, better still, a sky full of shooting stars. The appearance is as though the screen were being fiercely bombarded by an incessant rain of projectiles, each impact being marked by a flash of light, just as sparks fly off from an iron when it is struck with a hammer.
The history of science scarcely affords a more striking instance of the fulfilment of scientific prophecy. Since 'helium' (the element which was first discovered in the sun, by means of a line in the solar spectrum which did not agree with the lines of any of our known elements, and which was discovered on the earth only a few years ago by Lord Rayleigh and Professor Ramsay) is found in nature only in connection with radio-active minerals, i. e., in connection with those minerals which contain uranium, thorium or radium, Rutherford predicted that helium would one day be found to be one of the ultimate products of the disintegration of the radio-active elements.
By the ordinary process of decay, all organic compounds, which represent very complex molecular structures, are continually disintegrating into simpler ones, and in so doing are setting free the energy which was put into them when the processes of life built them up into complex forms. Similarly, the studies of the last eight years upon
The action of an incandescent body on a flame, or that of a flame on another flame, is certainly a common phenomenon. If it has remained unnoticed up to the present, it is because the light of the source prevented the observation of the variations in glow of the receiving flame. Quite recently I observed another effect of the "N" rays. It is true that these rays are unable to excite phosphorescence in bodies which can acquire this property under the action of light, but when such a body—calcium sulphide, for instance—has previously been rendered phosphorescent by exposure to sunlight, if it is then exposed to "N" rays—for instance, to one of the foci produced by a quartz lens—the phosphorescent glow is observed to increase in a very marked fashion; neither the production nor the cessation of this effect appear to be absolutely instantaneous. Of all the actions producing "N" rays, this is the one which is most easily observed. The experiment is an easy one to set up and to repeat. This property of "N" rays is analogous to that of the red and infra-red rays discovered by Edmond Becquerel. It is also analogous to the action of heat on phosphorescence.
Its variations in glow allowed of four foci being found in a pencil which had passed through a quartz lens; these foci are the same as those detected with the small spark. The small flame behaves therefore, in regard to "N" rays, just like the spark, save that it does not allow of the observation of polarization phenomena. In order to study more easily the variations in glow, whether of flame or spark, I examine them through a plate of ground glass, about 25 or 30 mms. distant. In this way one obtains,  ​ instead of a very small, brilliant point, a luminous patch of about 2 cms. diameter, of much less luminosity, whose variations can be far better appreciated by the eye.
The action of an incandescent body on a flame, or that of a flame on another flame, is certainly a common phenomenon. If it has remained unnoticed up to the present, it is because the light of the source prevented the observation of the variations in glow of the receiving flame. Quite recently I observed another effect of the "N" rays.
It is true that these rays are unable to excite phosphorescence in bodies which can acquire this property under the action of light, but when such a body—calcium sulphide, for instance—has previously been rendered phosphorescent by exposure to sunlight, if it is then exposed to "N" rays—for instance, to one of the foci produced by a quartz lens—the phosphorescent glow is observed to increase in a very marked fashion; neither the production nor the cessation of this effect appear to be absolutely instantaneous. Of all the actions producing "N" rays, this is the one which is  ​ most easily observed. The experiment is an easy one to set up and to repeat.
Everything we examined (3) — 2 independent sources
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