Chalcedony includes minerals like agate, onyx, jasper, and heliotrope. Chalcedony has a waxy lustre and is usually translucent to opaque. Key characteristics of Chalcedony include its hardness (around ...

The geochemistry of agate and chalcedony in volcanic rocks represents an intricate record of silica precipitation and crystallisation processes occurring under variable thermal and chemical conditions ...

Imagine a tool from the Stone Age. You're probably thinking of something in the shape of a leaf, with at least one of its sides fashioned into a point. But whether that point is sharp or blunt, smooth ...