For years there is confusion regarding the actual mineral composition of the Moon Stones (Orb of the Moons) included in the standard editions of Ultima VI - some people believe it to be real 'stone' (as in Quartz), others favor the idea of industrially made glass orbs.
This test will try to shed some light on this issue and possibly find any material differences.

These are the two test specimen: 1 Orb of the Moons (medium translucency), 1 Smoke Quartz Crystal:



Since crystalline Quartz is harder than amorphous glass it should be possible to scratch the surface of a glass object with the sharp edges of the smoke quartz crystal:



The result was indeed a clearly noticable mark on the shiny polished surface of the orb.
Which again means that the material used for these 'stones' cannot be natural quartz but rather ordinary artificial glass:



Moon Stones used as Ultima VI trinkets exists in numerous shapes and variations. Some of them are almost completely black and opaque, others have speckles and certain color anomalies and there are different levels of translucency. The clearest and most regular specimen of them were actually hand-picked for the 10th Anniversary Special Edition of Ultima VI.

They are all of the same material however: Glass. ;)