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Could anyone help me describe these rocks?

 
 
tbh123
 
Reply Tue 19 May, 2015 08:44 am
http://i.imgur.com/YIvatzz.jpg (1st rock)
http://i.imgur.com/E164pxL.jpg (2nd rock)
http://i.imgur.com/IQb1anl.jpg (3rd rock)

I have a combination of igneous, metamorphic and sedimentary rocks that I need details about. If anyone could help me name and give additional descriptions of the lithology, texture, mineralogy, fabric and synthesis of these rocks, it would be of much help and appreciation to me Smile Thank you!
 
dalehileman
 
  1  
Reply Tue 19 May, 2015 10:18 am
@tbh123,
1), Tbh, igneous, clearly granite
2) Metamorphic form (as a former rockhound I used to know) but which doubtless another a2k'er will name. Forced into the curvy patterns by underground forces
3) Clearly sedimentary, a sort of solidified mud containing a whole lot of seashells

https://www.google.com/?gws_rd=ssl#q=igneous+metamorphic+sedimentary&btnK=Google+Search

Thanks Tbh for the chance to guess. Others will chime in, I can almost guarantee, with detail
dalehileman
 
  1  
Reply Tue 19 May, 2015 01:34 pm
@dalehileman,
Where is everyone
0 Replies
 
Lordyaswas
 
  1  
Reply Tue 19 May, 2015 01:39 pm
Who said that?
dalehileman
 
  1  
Reply Tue 19 May, 2015 01:44 pm
@Lordyaswas,
Lordy, who said what
Lordyaswas
 
  2  
Reply Tue 19 May, 2015 01:53 pm
@dalehileman,
Oh, it's you.

There I was, minding my own business and whistling to myself as I walked down what I thought was a deserted corridor of A2K, and suddenly someone whispered "where is everyone?"


Fair made me jump out of my skin.
0 Replies
 
tbh123
 
  1  
Reply Tue 19 May, 2015 02:08 pm
@dalehileman,
Thanks so much for your insight. Would it be safe to say the metamorphic rock to be Gneiss?
dalehileman
 
  1  
Reply Tue 19 May, 2015 04:02 pm
@tbh123,
Quote:
Thanks so much for your insight.
You're welcome Tbh for what it's worth

Quote:
Would it be safe to say the metamorphic rock to be Gneiss?
Yes, I vaguely recollect

https://www.google.com/?gws_rd=ssl#q=illustration+gneiss
farmerman
 
  3  
Reply Tue 19 May, 2015 05:50 pm
@dalehileman,
The firt one is probably a granodiorite. (Granites have lrger feldspars and they are mostlly pink. This one hs more Ca than K in the feldspars. Granite is sort of a good term because its a grouping and granodiorite is a specific type of rock based upon crystal sizes, felldspar hemistry, prcent free quartz and evidence hether its volcanic or magmatic. The rock is special because, after it was emplaced, it was broken off its llens and then apparently rolled in a stream or dragged in a glcier. Its rounded pretty well. Glacially drug rocks usually have some flat "sanded sides" while stream rolled rocks are rounded more.


The second is definately a gneiss probably a hornblende gneiss.
Lota quartz and K Feldspar so its a fairly high egree of metamorphism

The third is definately a fossiliferous silty sandstone or sandy iltstone . Its not too cemented so it has undergone "partial hardening"The fossils are what we call a "Shell hash", which means its probably a death assemblage of dead shells that wre being tossed around and crunched in a moderate energy environment. There are Mercenaria (steamers) Lyropecten (Small scallops) and some other s I couldnt identify cause theyre mostly just chunks
Id say these were probably from Mid Cenozoic or later (Miocene to Pleistocene)






dalehileman
 
  1  
Reply Wed 20 May, 2015 10:40 am
@farmerman,
Quote:
Granites have larger feldspars and they are mostlly pink
Ah yes now I remember, Man

But thanks for your clarifications
0 Replies
 
 

 
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