Summary of Glaser's recipe for making the Antimony glass (1667):

Take any amount you want of "Antimony" (Note "Antimony" is the ancient
name of Stibnite and is not our modern metal Sb. Be aware of this
important point ...) and crush it. Put the powder in a strong and wide
vessel and calcinate in a good fireplace. Take greatest cares of the
toxic fumes. Shake the powder during all the calcination in order to
avoid its agglomerates. If such a problem occurs, crush the Antimony in
a mortar and calcinate it again. Calcinate the Antimony until the fumes stop and its color becomes similar to ashes. Put the calcined Antimony in a strong crucible. Make a violent fire in order to fuse the Antimony. Taking a sample of the matter with a rod of
iron, you 'll see the good moment for stopping the fusion.
Poor the content of the crucible in a wide plate of copper and you'll
obtain a beautifull glass of Antimony.

Glaser proposes a recipe for purifying this glass. You have to mixt 2
parts of glass with 3 1/2 parts of well purified saltpetre. Poor the
mixture in a hot crucible (spoonfull by spoonfull). When all the mixture
is liquid, stop the operation. Crush the result in order to obtain a
very subtle powder and mixt it with (slightly) hot water.
Decante the water in order to obtain a coarse powder and put the
remaining liquid in a vessel where a very subtle powder of Antimony
glass will be obtained.