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<p>[QUOTE=&quot;Miscstuff, post: 9606952, member: 1331&quot;]Bit late to the game here but as a hobby opal cutter I&#039;m going to go out on a limb and say they are not modern cracks. The whiteness of the webbing suggests to me they cracked sixty million years ago and the cracks refilled with white common opal (potch). There is a name for that but I&#039;m stuffed if I can remember it. Anyway there should be nothing to worry about as the potch glued it back together.</p><p>&nbsp;&nbsp; As for long term reliability about one in ten to fifteen might develop a crack after ten years or so but data is hard to find on the subject. Most cracking is caused by bumping against hard surfaces or thermal cycling i.e. hot inside the house, cold outside the house on your way to shopping etc. Note- this is for Australian opals which are almost all sedimentary and don&#039;t absorb moisture unlike volcanic opals from generally the rest of the world that crack like crazy.<img src="styles/default/xenforo/clear.png" class="mceSmilieSprite mceSmilie17" alt=":bag:" unselectable="on" unselectable="on" />[/QUOTE]</p><p><br /></p>

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