atomic number
melting point

1. Mix a tiny amount of powdered mineral with sodium carbonate flux, then fuse the mixture with the blowpipe flame, dissolve the fused bead in a solution of dilute HCl and allow it to evaporate; all silicate minerals will yield a silica gel as a result of this test.

2. Heat a small portion of sodium metaphosphate flux in a hot flame until it forms a fused globule, then dip the hot bead into a bit of powdered mineral sample; a skeleton of undissolved silica will be left in the bead after it has cooled.