enter image description hereenter image description here no known origin,its opaque its 2 1/4" leaves no streak, has a hardness of 6-6 1/2 I drilled it with a diamond plated bit,it is a very tough stone.It weighs 2ozs 56.6 grams.When I drilled it the powder from the hole was whitish, afterward it was the same green color right through the hole.I was not able to determine its density.This stone is not magnetic.Has some very thin dark lines that are on both sides. ]3]3


Without anymore information, best guess is that your rock is metamorphic quartzite based on texture and color. Does the rock feel about the right weight for its size? If yes, that would also suggest the rock is a quartzite.

Try to measure the specific gravity, it will help narrow the identification. Specific gravity testing example from http://www.johnbetts-fineminerals.com.

Other possibilities: Jadeite - Usually translucent and somewhat waxy luster. Not a good match for your rock. Amphibolite - Can be dark in color but typical has a more grainy texture than your rock. Serpentinite - Minerals that compose serpentinites are more dense than quartz (specific gravity 2.65). These minerals have specific gravity > 3.0

  • $\begingroup$ I don't have a digital gram weight to do a density test,I'll have to find one, I think that Nephrite might be a possibility, I understand that Nephrite can be opaque,this is way harder than serpentinite, drilling this rock with a diamond plated bit took a half hour and keeping water on it.To my understanding quartzite is translucent unlike this stone.I agree a density test would put it to rest, Thank you Gary Kindel $\endgroup$ – Dave Jan 31 '19 at 15:57
  • $\begingroup$ Just wondering if it could be green chert, seeing it was so hard to drill $\endgroup$ – Dave Feb 1 '19 at 19:53
  • $\begingroup$ Probably not chert. Chert is sedimentary and the rock is metamorphic so chert would become quartzite. $\endgroup$ – Gary Kindel Feb 1 '19 at 22:46
  • $\begingroup$ I see what your saying and I respect your experience in geology, I'm a newbie and eager to learn more about the complex world of rocks. Thanks Gary Kindel for sharing your knowledge here. $\endgroup$ – Dave Feb 1 '19 at 23:32
  • $\begingroup$ I found a digital gram weight and discovered the rocks density is 2.578 so you are correct Gary Kindel with metamorphic quartzite, I have a nice piece of nephrite jade that was dry weight 101g and it turned out at 34g immersed in water then divided with the dry weight came out at 2.970 proving its nephrite.So this rock here is metamorphic quartzite. $\endgroup$ – Dave Feb 4 '19 at 16:37

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