Mindat Logo

rock needs ID

Posted by craig johnson  
rock needs ID
March 07, 2013 07:41PM
sedimentary or metamorphic ?
open | download - 000_0997.JPG (414.2 KB)
avatar Re: rock needs ID
March 08, 2013 04:54PM
Craig, from what I can see in the photo, I would go with sedimentary. The particles appear to be quite mixed in size and it looks like the rock broke around particles and not through them (although a real close-up would help determine that). There is a slight indication of what could be foliation at the top, but I think it is an artifact.
Re: rock needs ID
March 09, 2013 01:54AM
Thanks for your reply Donald, The rock does react with hydrochloric acid, There looks to be some grain break opposite of the planar cleavage surfaces and are shiny spots through the break of the rock. Would that indicate a marble or would it be limestone ?
avatar Re: rock needs ID
March 10, 2013 04:34PM
If it fizzes everywhere with acid It would be limestone. If only in isolated spots, it could be another type stone containing small amounts of calcite. I would put my money on the limestone.
Re: rock needs ID
March 10, 2013 07:38PM
Hi, The rock might be a calcite cemented clastic sedimentary rock, such as sandstone. I'd try scratching a piece of glass with it. It it scratches glass, it's probably calcite cemented sandstone. It might also be a calcarenite--essentially a calcite sandstone. In either case, it looks sedimentary to me.

Your Email:


  • Valid attachments: jpg, gif, png, pdf
  • No file can be larger than 1000 KB
  • 3 more file(s) can be attached to this message

Spam prevention:
Please, enter the code that you see below in the input field. This is for blocking bots that try to post this form automatically. If the code is hard to read, then just try to guess it right. If you enter the wrong code, a new image is created and you get another chance to enter it right.
Mineral and/or Locality  
Search Google  
Copyright © Jolyon Ralph and Ida Chau 1993-2014. Site Map. Locality, mineral & photograph data are the copyright of the individuals who submitted them. Site hosted & developed by Jolyon Ralph. Mindat.org is an online information resource dedicated to providing free mineralogical information to all. Mindat relies on the contributions of thousands of members and supporters. Mindat does not offer minerals for sale. If you would like to add information to improve the quality of our database, then click here to register.
Current server date and time: December 19, 2014 15:03:38
Mineral and Locality Search
and/or Locality:
Fade toolbar when not in focusFix toolbar to bottom of page
Hide Social Media Links
Slideshow frame delay seconds