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<p>[QUOTE=&quot;Bronwen, post: 4508626, member: 5833&quot;]Bronwen humbly admits she did not look closely at the title, or she would have seen that you already know perfectly well it&#039;s a bookend.</p><p><br /></p><p>Now, on this subject:</p><p><br /></p><p><br /></p><p><br /></p><p><br /></p><p>The word &#039;onyx&#039; comes from the Greek for fingernail.&nbsp; These days, in the US at least, when people say &#039;onyx&#039;, they really mean black onyx, which is something that does not occur in nature; it is dyed to be that dark.&nbsp; This is such a common, widespread &amp; ancient practice that it is not considered necessary to mention it.</p><p><br /></p><p>The stone used for the second cameo of Urania I showed is designated as sardonyx: the background layer is dark brown sard; the figure is engraved in the onyx layer. It is all the mineral chalcedony, a form of quartz.&nbsp; Carnelian/cornelian is in this family, as are bloodstone &amp; jasper.</p><p><br /></p><p>The material used for the bookends is also commonly called onyx.&nbsp; However, my very good gemstone book calls it &#039;onyx-marble&#039;, a stone quite different in composition &amp; properties than chalcedony onyx, the mineral the Greeks had in mind.&nbsp; It is calcium carbonate based, much softer than the silicon-based quartz.[/QUOTE]</p><p><br /></p>

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