McRocks is not a club and therefore has no membership requirements.
No matter if you are an experienced or newbie rockhound,
we encourage all good people to post messages on McRocks.
The only stupid question here is the one you don't ask!

 
Click the following picture for an illustrated
tutorial on how to post images on the board.

Please don't use IMAGESHACK.US to post images.
Other image hosting internet services are OK.

For tons more rockhounding information:

Welcome to McRocks!
Your hosts, Mike & Chrissy Streeter

Attention Mozilla Firefox Users
Since a login is not required for this message board,
it is totally secure. However, if you're still concerned
about security, you can click on the following link
Click here for McRocks Secure Message Board

 
 
 


Reply
  Author   Comment  
BParker
 #1 
Hey Guys and Gals,

On a recent rock hunt in KY I picked up a chunk of what I thought at the time was petrified wood.(I had petrified wood on the brain after just returning from Oregon).  It was laying in the grass at a road cut near Mt Vernon. Its a sizeable piece, about 12 inches across, and weighs around 15-20 pounds.  Now the more I think of it, I am not so sure it's wood. Maybe it could also be coral?  It has some what looks like agate in it.  Thoughts?

Here are a couple pics:







Mike Streeter
 #2 
See if you can you easily scratch the side of it with a pocket knife blade.  Then, if you can scratch it, put a few drops of white vinegar on the scratch to see if there is a fizzy reaction - you'll probably have to look real close with a magnifying glass to see tiny bubbles rise off the surface (muriatic acid diluted to around 10% works better).  If you can scratch it with a knife blade and the rock reacts when exposed to vinegar or muriatic acid, then it is most likely some sort of limestone fossil that has been partially replaced with agate (silica) and not petrified wood.
Bob Harman
 #3 
Looks like a limestone based rock structure called a styolite. I see them quite often here in Indiana.  Neither petrified wood nor a fossil in the usual sense of the term.    BOB
Bob Harman
 #4 
As an addendum, google "styolites".   There you will see several pictures of them from differing angles. Looking across the top of a flat piece of limestone, they are seen on end, resembling an irregular jagged crevice.    Take a heavy crack hammer and break the limestone following the jagged crevice and you will see the styolite from the side, which is what your picture is showing. From the side the structure resembles many parallel side by side columns like your photo.     They may occur with fossils, but are not themselves a fossil. They are considered a pseudo-fossil.     BOB
Previous Topic | Next Topic
Print
Reply

Easily create a Forum Website with Website Toolbox.

Return to Message Index Page

 

 

LINKS

US & STATE GEOLOGICAL SURVEYS
MEMORABLE MESSAGE BOARD PICTURES
McROCKS PHOTO ALBUM
FIELD TRIP REPORTS
MINERAL IDENTIFICATION KEY II
MINDAT.ORG
IMAGE POSTING TUTORIAL
ROCK & GEM MAGAZINE
GEMHUNTER'S McROCKHOUND LINKS
McROCKHOUND BIOGRAPHIES