Glowing Rocks!

Rocks that glow or fluoresce.There are four luminescent properties that minerals can exhibit.Fluorescence,triboluminescence,tenebrescence and thermoluminesence.These are all physical processes which minerals exhibit when exposed to different activators.

Fluorescent minerals will give off a glow when they are exposed to shortwave ultraviolet light or longwave ultraviolet light.The colors and combination of colors is amazing.The beauty is truly one of the wonders of the mineral kingdom.Fluorescence in minerals has useful purposes also.It has been used in mining as some ores have a glow to them.This was a way of separating good ore from scrap rock.Also the study of fluorescent minerals led to the making of color TV screens.

Another property called triboluminescence can make rocks glow.When certain rocks are scratched,crushed ect...they emit a small amount of light.This property can be see with the mineral sphalerite and also tremolite.When you rub two pieces of tremolite together it will give of sparkes of an orange color.

Tenebrescence is yet another luminescent property.Some rocks actually can change color when exposed to ultraviolet light,the sunlight or darkness.One mineral which often exhibits this property is hackmanite.It develops a red,pink color when exposed to SW UV light.Some hackmanite will also turn red/pink in sunlight if left there over time.And the opposite effect can happen in other hackmanite where the color will fade in sunlight.

Thermoluminescence is a property which causes a mineral to glow when heated.Some fluorite will glow when exposed to heat.Chlorophane which is a variety of fluorite will sometimes glow after you hold it in your hand.It is so sensitive that the heat from your hand can make it glow.

So yes rocks can and do glow.