Scheelite

Scheelite – Ca(WO4)
Elements: Calcium, Tungsten, Oxygen
Class: Tungstates
Crystal System: Tetragonal
Hardness: 4.5-5
Apatite
Talc (1)Diamond (10)
Softer than glass. A steel knife scratches it.
Origin: Pingwu Beryl Mine, Mt. Xueboading, Mianyang Prefecture, Sichuan Province – China
Did you know?

The metal locked in scheelite, tungsten, has the highest melting point of any metal, near 3,400 degrees Celsius. That is why it was the glowing thread inside the old light bulb, and why it tips the tools that cut all other metals. The heavy stone in your hand carries the most heat resistant metal on Earth.