Chromium
Cr
atomic number
24
melting point
1907°C

1. Mix a small portion of powdered mineral with borax flux, then immerse the mixture in the oxidizing portion of the blowpipe flame; the fused bead will be yellow to red in color (depending on the amount of chromium present) when hot and yellowish-green when cool; exposure to the reducing portion of the flame produces a green-colored bead which undergoes no change in color as it cools.

2. Mix a small portion of powdered mineral with sodium metaphosphate flux, then expose the mixture to either the oxidizing or reducing portion of the flame (in this case, it doesn’t matter); the fused bead will be a dirty green color when hot which gradually turns to a beautiful clear green as it cools.

3. Mix a small portion of powdered mineral with sodium carbonate flux, then expose the mixture to the oxidizing portion of the blowpipe flame; the fused bead will be a dark transparent yellow when hot, and an opaque light-yellow when cool.