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What Stone is That?

Rock&Gem Magazine

|

August 2025

An excerpt from The Minerals Encyclopedia by Rupert Hochleitner, the Deputy Director of the Mineralogical State Collection of Munich since 1993, with a doctorate in mineralogy with an expertise in systematic mineralogy. (Firefly Books, 2022)

What Stone is That?

This question occurs again and again, whether you pick up a pebble while walking, find a crystal in the mountains, find gold or silver shiny chunks in a spoil heap at an ore mine, trip over the curb or look at a beautiful piece of jewelry. Time and again, you want to know what that mineral is, what kind of rock lies before you, what type of gemstone glitters with such beautiful colors.

The purpose of this book is to answer such questions — as a constant companion when hiking, travelling, mountaineering, collecting minerals or when searching quarries and spoil heaps, at mineral fairs and even at the jeweler’s.

There are a few basic points to keep in mind:

With the exception of mercury, minerals are always solids. No matter how good mineral water may taste, no matter how many minerals it shows on the label, it is still a liquid and therefore not a mineral.

Anything man-made, from window glass to the quartz crystal in a wristwatch to an artificial diamond, is not a mineral. A mineral must always be of natural origin.

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