He recounts moreover some other properties of this Crystal; to wit, that when rubbed against cloth it attracts straws and other light things as do amber, diamond, glass, and Spanish wax.

Let a piece be covered with water for a day or more, the surface loses its natural polish.

When aquafortis is poured on it it produces ebullition, especially, as I have found, if the Crystal has been pulverized.

I have also found by experiment that it may be heated to redness in the fire without being in anywise altered or rendered less transparent; but a very violent fire calcines it nevertheless.

Its transparency is scarcely less than that of water or of Rock Crystal, and devoid of colour.