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<p>[QUOTE=&quot;Bronwen, post: 2031548, member: 5833&quot;]In the beginning there was quartz.</p><p><br /></p><p><u>Macrocrystalline quartz</u>.&nbsp; Amethyst (purple), citrine (yellow), rose quartz (pink), rock crystal (colorless).&nbsp; I sometimes see jewellery using something labeled as &#039;green amethyst&#039;.&nbsp; To me this is an oxymoron but perhaps it&#039;s made by applying some treatment to amethyst.&nbsp; Most deeply colored citrine available now started out as amethyst.</p><p><br /></p><p><u>Microcrystalline quartz</u>.</p><p>Chalcedony.&nbsp; Translucent.&nbsp; Pure form a milky white/grey/blue/lavender.&nbsp; Orange/brown material called carnelian (US)/cornelian (everywhere else) or sard.&nbsp; Sard is darker than cornelian but where the line is drawn is subjective.&nbsp; I reserve &#039;sard&#039; for stone that is much darker brown than these beads.&nbsp; Some of it looks black until you put a light behind it.&nbsp; Chalcedony is porous &amp; has been dyed since at least Roman times.</p><p><br /></p><p>Jasper.&nbsp; Opaque.&nbsp; Any color.&nbsp; Solid, banded, speckled, mottled.&nbsp; Bloodstone/heliotrope, deep green with red speckles, is a jasper with a commonly recognized name of its own.</p><p><br /></p><p>It surprises me that the Presidium generally gets no reading for glass.&nbsp; After all, it is not chemically very different from quartz.&nbsp; Does your machine register anything softer than the quartz family of minerals?[/QUOTE]</p><p><br /></p>

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