# Any geologists among us?



## AverageWhiteBloke (12 Jun 2010)

I'm thinking of getting some stone locally I live near both the beach and the lakes so should be able to find some interesting looking pieces. Is there anything to watch out for that might be detrimental to water quality? I was thinking of just testing with vinegar for hardness.


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## David.Earl (12 Jun 2010)

I could call myself a geologist, i've got a A level in it!
I'd look out for any rocks with veins in them, as a white vein which looks like quartz could be calcite, which could have negative effects on water chemistry.
Also, I'd stay away from any sandstones, or other fine grained soft sedimentary rock. Just because the matrix with holds the sediment particles together could leach some bad stuff into the water, and the rock would eventually crumble. 
Hope this helps a little.

David


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## Nick16 (13 Jun 2010)

you want hard rock. if you find some similar pieces. wack one bit with a rock. if it 'snaps' then its good. if it crumbles then its not! 

yep, avoid anything with nasty 'veins', holes etc. 

you will need to boil the stones to get rid of some of the outer crap. 

dont worry, i wont report you for stealing stones off the beach......


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## AverageWhiteBloke (13 Jun 2010)

> yep, avoid anything with nasty 'veins', holes etc


That's a shame some of the veiny rocks look well.


> dont worry, i wont report you for stealing stones off the beach......


  There actually is a sign up at the beach, I think I should be ok with a couple it's more for people pulling up with a trailer to get back fill for there patio. I might wear a ski mask just in case though  
When I get some I'll post some pics to see what you think.


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## peter1979 (13 Jun 2010)

Doyouknow what sort of rocks are in the area you are collecting from?  I have been studying geology at BSc level for a few years but to be honest its not always possibleto ID a rock at sight, you will sometimes need lab equipment and a microscope.  But generally avoid limestone,anything with calcite looking veins, and sedimentary rocks like sandstone or conglomerates.  Ideally rocks like slate, a metamorphic rock, or schists, and igneous rocks are best suited.  I would take care boiling rocks.  If you do this, make sure it is only for minutes at most.  Rocks take a long time to heat up,but have a capacity to hold heat for a long time, also if they are cooled quickly they can explode spectacularly!  Just be careful not to over do it.
Best if you can grab some good looking rocks,do the acid/vinegar test to see if they fizz, if they dont then take some pics post them on here and we'll see if they are ok.


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## dw1305 (14 Jun 2010)

Hi all,
Because you are in Cumbria you should have access to a lot of really good hard igneous pebbles. Any hard round beach pebble or cobble should do.

You get them in a range of colours, the granite pebbles will be white or pink with a darker speckling, gabbro coarsely speckled dark and light etc.

This is a typical Granite.





Have a look here for some more:
http://geology.com/rocks/igneous-rocks.shtml and also at the metamorphic rocks http://geology.com/rocks/metamorphic-rocks.shtml. I picked up some stripy Gneiss  and fantastic shiny green Peridotite? pebbles in N. Pembs last time I was there.
Gneiss




cheers Darrel


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## AverageWhiteBloke (14 Jun 2010)

I will post any I find.


> Because you are in Cumbria you should have access to a lot of really good hard igneous pebbles. Any hard round beach pebble or cobble should do.


I'm trying to get hold of an angled rock with some shape to it to get a bit of dimension to an already bland scape, the safer stones come from the beach but are generally rounded or pebbles as they are known   there is plenty of granite and slate in the lakes though just haven't got out there yet.

Thanks for the warning on the boiling appreciated.


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## dw1305 (15 Jun 2010)

Hi all,
If you are after angular rocks what you want is a disused hard rock quarry, either for roadstone or an old mine for silver, gold, lead zinc etc. I think they are marked on the OS map.

Another possibility is some scree, there is a huge block scree running up from Waste water, but  any scree which has Parsley Fern (_Cryptogramma crispa_) on it will be acid rocks. There must be some scree accessible from the tops of some of the passes? Wrynose etc?  

cheers Darrel


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## Hokum (10 Aug 2010)

Would i be correct in thinking though, that if you want hard water for your fish, that a rock which reacts lightly to acid maybe a good idea to act as a buffer? I didn't do Geology... I did chemical engineering


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## dw1305 (12 Aug 2010)

Hi all,
I'm in Germany so I've got limited WWW access, but yes a limestone will buffer the KH of the water  by adding carbonate via the carbonate\carbonic acid equilibrium, and GH via the calcium ions.

Some limestones are very hard (Carboniferous limestone in the UK), but softer ones are any shell derived aragonite form of calcium carbonate and chalk, sugar  or jurassic limestones. That is why people use coral or shell sand, it is more soluble.

cheers Darrel


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