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ID HELP. Quartz, beachstones...
  
  Index -> FOR BEGINNERS: What is it? Where is it from?
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Maine




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PostPosted: Apr 19, 2019 14:43    Post subject: ID HELP. Quartz, beachstones...  

Please save me from myself!

A year ago I moved to Maine because I love beachcombing for seaglass. However, now I find myself obsessed with rocks, and I can’t stop bringing them home. Unfortunately I know little about them. I have read online, and looked at pictures and I’m just not getting the answers I need; mostly on quartz. I have attached an overwhelming amount of rocks, that if I could identify would help me understand what I have here and what I can stop bringing home. I can post better pictures if needed, but I figured a trained eye would have no problem identifying.

All of these came from the coast of DownEast, Maine. Please let me know if you can help. Thank you!



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Bob Harman




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PostPosted: Apr 19, 2019 15:09    Post subject: Re: ID HELP. Quartz, beachstones...  

Maine, Welcome to this forum

What I see is all your examples being water rounded pebbles of microcrystalline quartz, also called quartzite, not otherwise specified (nos).

For quartz variety names, I use a narrow definition, reserving the name "milky" quartz for saturated white Crystals of quartz and the name "smoky" quartz for Crystals of gray thru black quartz. Amethyst being a bit of a special case.

Others might just use the shade of the quartz specimen to name it, but I prefer the narrower definition, using the shade plus the actual crystal to name the quartz variety.

So, for me, all whitish thru gray color shades of beach pebbles of quartzite are just that, nos, no special quartz variety naming. Others might have a different view. Bob
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Kevin Schofield




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PostPosted: Apr 19, 2019 15:39    Post subject: Re: ID HELP. Quartz, beachstones...  

Maine wrote:
Please save me from myself!

A year ago I moved to Maine because I love beachcombing for seaglass. However, now I find myself obsessed with rocks, and I can’t stop bringing them home. Unfortunately I know little about them. I have read online, and looked at pictures and I’m just not getting the answers I need; mostly on quartz. I have attached an overwhelming amount of rocks, that if I could identify would help me understand what I have here and what I can stop bringing home. I can post better pictures if needed, but I figured a trained eye would have no problem identifying.

All of these came from the coast of DownEast, Maine. Please let me know if you can help. Thank you!


Hi Maine,

first thing to say is that you won't get much help here to solve the problem of your addiction. We all have that problem, and this group isn't so much a mutual support group as a mutual encouragement group!

On the matter of your rocks, it looks to me as if the great majority of what you have is quartz of one form or another. Some may be vein quartz (the stuff that fills the fractures in rocks), for example the one above the "a" of "all quartz" in your first picture. Some others look like quartzite...a rock made up entirely or mostly of quartz. These can be sedimentary (cemented sandstones) or metamorphic (baked sandstones). The big triangular one at top left of your first picture looks as if it is one of the latter. The three in the second row of the second picture might just be the former.A third possibility is cryptrocrystalline quartz (chalcedony, flint). Top left in the first picture is a possibility (flints are often dark-coloured).

The one that you are most curious about looks to be more of the same, except that it has managed to acquire a bit of natural polish (or maybe it was somebody's much loved pet rock and lots of gentle fondling polished it up...)

Because Maine has a lot of very old, very hard and very altered rocks another possibility for something white, round and abraded is a piece of marble (metamorphosed limestone), although because marble is quite soft compared to quartzite they will be relatively scarcer (rapidly grind down to nothing). You could test to see if any of yours are marble by trying to scratch them with a steel blade. Marble will scratch, quartzite won't.

Happy hunting...

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Veni, Vidi, Emi
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Wynnek




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PostPosted: Apr 19, 2019 15:43    Post subject: Re: ID HELP. Quartz, beachstones...  

With beach pebbles, love the shape, love the color, love the feel, but don't try to identify. Some things are best enjoyed as nature 's art. Pick one and meditate on it. ;-)
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alfredo
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PostPosted: Apr 19, 2019 16:45    Post subject: Re: ID HELP. Quartz, beachstones...  

Some of your more coarse-grained greyish colored pebbles are probably slightly "smoky" quartz derived from pegmatites. Quartz gets that smoky color after being exposed to low level of radioactivity for long periods of geological time.
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SteveB




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PostPosted: Apr 19, 2019 22:08    Post subject: Re: ID HELP. Quartz, beachstones...  

Beach finds can have their own charm and these are typical quartz / quartzite examples. Nothing special to warrant additional names. Many names have been arbitrarily given to create sales of useless/wotrthless specimens. Particularly in the new age market segment.

What would be more interesting for you could be to find where the quartz is coming from, it doesn’t form as pebbles like these. Try looking nearby for cliff faces where there may be a white seam running through the quartz may have broken out from. Where quartz forms deep underground the conditions can form nice crystals which you might find in the cliffs. Once it falls into the water the wave action wears them down into pebbles. Plus there are often other interesting minerals and metals associated with quartz which are also brought to the surface with large geological processes. Think of mixing the ingredients for a cake by hand, when your arm starts getting tired the mixture is probably not smooth and uniform yet, you might have a chunk of butter in once part, a clump of sugar or flour in iother parts. Same with mineralogy: changes in temperature, pressure and amount of elements means when minerals are in molten state its typically non-uniform. The chemical reactions can also produce gases that can form bubbles (cavities) where crystals can form or other liquid minerals can pool. Its a complex series of conditions that can often been noticed in large scale on the surface especially in cutaways like cliffs along beaces and roadsides. Seams of quartz are often large and white and stand out a long way away so easy to find. Go look up close and if you start finding facet faces try following them, likewise if the quartz starts getting clear or coloured just follow it as best you can to where it is at its “best” which represents where the conditions were once the best in that mix and is the most likely spot for finding interesting specimens. Its surprisingly exciting to find even the tiniest crystals in what at first looks like wasteland. Local librarie often have geological survey reports and maps made as prospectors looked over an area for very large mineral deposits that may be worth mining. For fossickers though it means there are good small pockets of minerals everywhere to be found for interesting specimens for your collection.
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