A mineral, called also sphalerite, and by miners mock lead, false galena, and black-jack. It is a zinc sulphide, but often contains some iron. Its color is usually yellow, brown, or black, and its luster resinous.
(b)
A general term for some minerals, chiefly metallic sulphides which have a somewhat brilliant but nonmetallic luster.
... tungsten filament emits light because it is sufficiently hot. A phosphorus match rubbed in the moist palm of the hand is seen to glow, although it is at an ordinary temperature. This may be termed "chemi-luminescence." Sidot blende, Balmain's paint, and many other compounds, when illuminated with ordinary light, and especially with ultra-violet and violet rays, will continue to glow for a long time. Despite their brightness they will be cold to the touch. This phenomenon ... — Artificial Light - Its Influence upon Civilization • M. Luckiesh
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