RiverOtter
spending too much on rocks
Member since January 2004
Posts: 339
|
Post by RiverOtter on Mar 25, 2004 11:44:29 GMT -5
|
|
|
|
Post by creativeminded on Mar 25, 2004 11:52:01 GMT -5
It would be interesting if you could cut it apart and see if there are more "Crystal Caves in it like the one that is exposed. Have you tested the hardness of the outside part of the stone?
Tami
|
|
donwrob
has rocks in the head
Member since June 2003
Posts: 509
|
Post by donwrob on Mar 25, 2004 13:14:48 GMT -5
I've seen rock like that, it may be a piece of flint or chert. It is pretty common for it to have quartz vugs or pockets of quartz crystals like that. It is hard to tell by the pic, but a good possibility. Later, Don
|
|
James
freely admits to licking rocks
Member since October 2003
Posts: 876
|
Post by James on Mar 25, 2004 14:03:30 GMT -5
Looks like a quartz crystal cavity in some sort of host rock.
|
|
|
|
Post by Original Admin on Mar 25, 2004 14:56:10 GMT -5
I'd go with James there, Quartz.
The outer rock looks sedimentary in the picture - almost as though you could scratch grains off it with your fingernail?
|
|
MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
|
Post by MichiganRocks on Mar 25, 2004 15:20:29 GMT -5
I agree Andy, really looks like sandstone with a pocket of quartzite. Sandstone is really just a very small conglomeration of quartzite anyway. If a pocket forms where crystals can grow, you will get some larger crystals. Sandstone around my area is found with those pockets all the time.
|
|
donwrob
has rocks in the head
Member since June 2003
Posts: 509
|
Post by donwrob on Mar 25, 2004 18:10:49 GMT -5
OK Otter, you have us all wondering now. I still think it is a piece of chert with a quartz pocket. If you feel comfortable with it, take a hammer and knock the pointy end off of it ( away from the quartz, so you won't hurt that part) so we can get a look inside the host rock. My guess is that the inside will be fairly smooth and probably creme colored. The sandy exterior I think is just a thin cortex, the side with the quartz sure looks like patina on chert to me. Please hit it for us...will ya?
;D Don
|
|
MichiganRocks
starting to spend too much on rocks
"I wasn't born to follow."
Member since April 2007
Posts: 154
|
Post by MichiganRocks on Mar 25, 2004 19:09:25 GMT -5
Don's right about the fact that it could be chert. The "sandstone" finish could just be a rind on the chert. I have seen that phenomenom with quartzite in sandstone and chert both (understandable since both are silica based rocks). I'm with Don, get out the hammer and.....  ps. Not to sound like a broken record, but information other than pictures can really help. For instance, how does the rock feel in your hand, is it rough and abrasive, somewhat greasy feeling, surprisingly heavy when you pick it up, that type of thing. Ron |
|
|
|
Post by puppie96 on Mar 26, 2004 2:23:54 GMT -5
I've seen a ton of it in MO, it's commonplace in and around rivers/streams; I have always semi-jokingly called it Missouri geodes or cave rock, since you see a lot of this as cave formations. This leads me to believe that it's crystals in limestone. There's a rock show this weekend, that should be a good opportunity to get some opinions. I know absolutely nothing about rock ID -- not entirely true, I've learned a few things, but not nearly enough to venture a guess.
|
|
donwrob
has rocks in the head
Member since June 2003
Posts: 509
|
Post by donwrob on Mar 26, 2004 9:38:21 GMT -5
Good point about other info Ron, it would be helpful. If it does turn out to be chert, we'll have to see if Otter will do the lick test on it. You sure can get a feel for silica content with a simple lick test. The smoother on the tounge it is the higher the silica. Of course you'll have to go around and lick a bunch of other rocks to have something to gauge it by ;D. Try not to let anyone see you, you get strange looks from people  believe me. Be careful with obsidian....scratch that....don't lick obsidian! Have you ever tried to get a bandaid to stay on your tounge? Not fun, ttyl, Don |
|
RiverOtter
spending too much on rocks
Member since January 2004
Posts: 339
|
Post by RiverOtter on Mar 26, 2004 11:21:23 GMT -5
Thanks all for the feedback. As soon as it stops pouring down rain, I'll take it outside and smack it with a hammer. I'll post more info on it once I do.
Otter
|
|
llanago
fully equipped rock polisher
Member since January 2004
Posts: 1,714
|
Post by llanago on Mar 26, 2004 11:52:28 GMT -5
I also think it's flint/chert because I found a piece that has a similar crystal formation on the outside on one side and the other side has been broken off and I can see the chert.
I would take a pic of it for comparison, but can't find it. Somebody either came along and took it off my table outside, or I put it in the 10 gallon rubbermaid tub with the rest of the rocks I have collected, waiting to either be thrown back or tumbled.
|
|
believe me. Be careful with obsidian....scratch that....don't lick obsidian! Have you ever tried to get a bandaid to stay on your tounge? Not fun, ttyl, Don
