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yserbey 10-15-2012 06:14 AM

found object
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while walking on the beach i found this stone, i a weird way, it look like clitoris. took to home, try to make a hole to display it on a proper socle, but it was impossible to do it, i take it to a friend wiz diamond tool, again it was impossible to make a hole ! what do u think this stone is?

Andrew Werby 10-15-2012 03:35 PM

Re: found object
Since it's obviously not a diamond, a diamond tool will cut it. But you probably weren't using the right tool to deal with it effectively. Most diamond tools should be used wet, so either pour water on it when cutting (use a GFI breaker to avoid shock hazard) or make a little dam around the place you want to make a hole and fill that with water. For large holes in stone (bigger than a few mm), a diamond core bit is used and the core broken away. It also helps to use some kind of drill press with these bits.

Andrew Werby

Dries 10-16-2012 12:40 AM

Re: found object
It looks to me like a silicified shell (fossil) and the reason it’s so hard is because of all the silica.

yserbey 10-16-2012 08:27 AM

Re: found object
2 Attachment(s)
i even put it on a lathe, nothing happend , just smoke!

Andrew Werby 10-17-2012 03:27 PM

Re: found object
It could be a piece of fossil shell replaced by micro-crystalline quartz (chalcedony). But quartz (silicon dioxide) isn't as hard as many gemstones that are commonly cut with diamond. It has a Mohs scale hardness of 7, the same as popular semi-precious stones like agate or jasper (both forms of micro-crystalline quartz).

Note that the Mohs scale of hardness isn't a linear scale; the difference between a 7 (quartz) and 8 (topaz) is not as much as between 8 and 9 (corundum), which itself is much softer than diamond. Here's a chart that shows both Mohs scale hardness and true hardness:

Andrew Werby

yserbey 10-18-2012 06:39 AM

Re: found object
many tanx for ur care.

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