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Post by mohs on Jun 24, 2009 0:33:30 GMT -5
any insights on what causes the fine grooving/weaving on this stone? The picture is fairly good. But the weave tightly distinct. Guess it could be called banding also. Will slab eventually thanks for looking ed
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Sabre52
Cave Dweller
Me and my gal, Rosie
Member since August 2005
Posts: 20,456
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Post by Sabre52 on Jun 24, 2009 8:29:34 GMT -5
That sort of pattern is common to lots of metamorphic rocks ie shist, gneiss etc. When put under great heat and pressure, layered rocks become elastic and patterns are twisted, contorted etc. That's why metamorphic rock are often called "changed rocks" The grooving or onionskinning in most cases is the result of variable weathering which causes uneven erosion of the stone surface. Most metamorphic rocks are of mixed mineral content and mixed mohs hardness. Therefore, the softer zones wear down faster than the harder ones causing an uneven surface....Mel
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Post by Hard Rock Cafe on Jun 24, 2009 9:56:27 GMT -5
From here it looks like wood. But I agree on the differential erosion.
Chuck
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Post by mohs on Jun 24, 2009 15:56:20 GMT -5
Right on guys! Here’s a pic from one of my text books that comes close to what you so excellently analyzed Mel The fingerprinting is all a way around this rock. So it formed under ground and was not broken because the grooving is all away around? I spotted this in what I call ‘landscape river rocks’. It stuck out because of the outside texture. I plan on stopping back by that particular lot and see if there are more of this kind. If these rocks were dug from the same pit/area then there should be more like it, I figure. It interesting because most landscape river rocks are of standard boring type. But then you find niches that are more unique.
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Post by Hard Rock Cafe on Jun 24, 2009 16:10:10 GMT -5
Yeah, around here it's pretty common to find Lakers in the landscape rock. It all comes from the same glacial till gravel.
Chuck
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Post by mohs on Jun 25, 2009 11:01:45 GMT -5
I haven't found anything real outstanding yet. Well I did find the heart this is a prime site. This path of rocks is about 1/4 mile long.
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riverbendlapidary
fully equipped rock polisher
Member since September 2006
Posts: 1,058
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Post by riverbendlapidary on Jul 28, 2009 16:46:40 GMT -5
Looks like water tumbled petrified wood. We see alot of this in the Rio Grande.
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