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In 1980 the Alvarez team proposed that an asteroid impact ended the Cretaceous. The idea was widely disliked. What eventually

Almost all the iron in every car, bridge and building on Earth comes from a rock that stopped forming roughly

A crystal that formed at high temperature can, as it cools, decide that it no longer wants to be one

Every gold rush in history was, at the start, a placer rush. Nobody in 1849 was sinking shafts into quartz

Diamond is not stable at the surface of the Earth. Every diamond you have ever seen is slowly, imperceptibly, trying

Write out the chemical formula of calcite and the chemical formula of aragonite and you get the same three symbols

Every museum and university geology department gets the same enquiry several times a month. Someone has found a heavy, dark,

Hold a quartz point and you can see the crystal. Hold an agate and you cannot see anything at all,

The usual explanation is that water drips, evaporates, and leaves minerals behind. That is not what happens. Caves are close

Switch off a UV lamp over a tray of fluorescent minerals and almost everything goes dark instantly. Occasionally something does