What kind of rock is this?

I found this rock in my backyard. The sparkle is what caught my eye. I picked it up and noticed it had
shell impressions on it. You can see the sparkle in the video, but they are much more noticeable
in person. There are a few teeny tiny holes that look like they have tiny crystal (?) specks in them. I don't know anything about rocks.

It would help to know where your back yard is (state...or area)!

Your rock appears to be vocanic in nature...seems to be igneous (after eruption)...so something of a pyroclastic...no help here....good luck!

reply to post by virraszto


Most likely sedimentary rock. Usually the most common source for shell impressions.

Perhaps this helps.

reply to post by virraszto


That's a cool dig,almost looks like a fossil of a fish.Or could be coral.Test it with a magnet who knows.

reply to post by jerryznv


Sorry, I should have mentioned that in my post. NW Ohio

Originally posted by virraszto
reply to post by jerryznv

 

Sorry, I should have mentioned that in my post. NW Ohio

Well depending on an on accurate estimated age...probably from the Larimide Eruption Period (empahsis on the title)...so I would think that it should be easily enough identified...(I heard someone say a magnetic test...not much help in this case)....however a mineral test would prove some elements out...and the fact that it contains some biological elements (as coal does....)!

So lets see if we can figure this out...does it respond to acid at all...and how many minerals can you positively identify?

Nevernind...just refer to the geologist here..www.abovetopsecret.com...

Originally posted by jerryznv
reply to post by jerryznv

 

So lets see if we can figure this out...does it respond to acid at all...and how many minerals can you positively identify?

Acid? What kind of acid? I can't identify any minerals.
I'm looking at the photos on that link.

Fossils, those are fossils. I have an uncle in Indiana with riverbeds full of brachiopods and other assorted fossils, they are fun to find.

After looking at some photos, I guess it might be Fossiliferous Limestone. I don't see any sparkles in the examples, but maybe they can't be seen in the photos.

Originally posted by virraszto

Originally posted by jerryznv
reply to post by jerryznv

 

So lets see if we can figure this out...does it respond to acid at all...and how many minerals can you positively identify?

Acid? What kind of acid? I can't identify any minerals.
I'm looking at the photos on that link.

Ya sorry about that...you were linked to a pretty advanced geological mineral identification site...although some would consider it elementary stuff...but in truth it is a bit tough to understand...that is why I was hoping to offer something other than a link!

Identifying minerals is not easy for most of us...and a igneous rock..(although sedimentary) means a rock...so we need some more help...your where I was at my first year in college!

You have a very common igneous rock...and given your location it probably date to the Larimide Eruption....(Yellowstone area type eruption)...most likely from a pyroclastic flow movement area that would most likely date you specimen somewhere around a million years old...so you have something interesting geologically for your area...but needs a bit more testing to be sure!

reply to post by virraszto


You have a very common rock...and you wasted time identifying it on ATS because you didn't do your own research...congratulations...you are a true ATS member!

Can you imagine the influx of people if this was an identify my rock site?

What kind of rock is this...or mineral...the whole "rock" is made up of it!



See what I mean?

reply to post by jerryznv


I did look at photos last night and also today trying to identify it. I have zero knowledge of rocks. I'm sorry to have wasted your time, but you didn't have to waste your time.

Originally posted by virraszto
reply to post by jerryznv

 

I did look at photos last night and also today trying to identify it. I have zero knowledge of rocks. I'm sorry to have wasted your time, but you didn't have to waste your time.

I haven't wasted my time...I was here anyway...just trying to help!

Glad you have it figured out!

Another ATS mystery solved!

Well, thanks everyone for the help. That was the only one of it's kind that I saw, in with a bunch of others. I was out in my garden today, getting the soil hoed and noticed a ton of tiny rocks in the soil. Those rocks
weren't there last year or if they were, they were buried deep. Since I found one interesting rock the other day, I picked up a lot of the ones in my garden bed. I haven't cleaned them off yet. I'm curious as to what I'll find.

What it looks like to me, without actually holding it in my hand, is a low grade non gem quality obsidian. Obsidian is what occurs when lava hits and instantly cools in water, thus the shell impressions. As it is actually a form of naturally formed glass any slight chip or clean spot will shine and shimmer. That's my guess. If you chip a piece of of it in a non impressioned area and it is obsidian you will know right away as it will shine and will look like black glass as well as break with very sharp edges. It does come in several forms like mahogany obsidian, which has brown in it and snowflake obsidian, which has white snowflake shapes in it as well. If it is not volcanic you will know right away, like I said, and can look at other possibilities.

reply to post by jerryznv


That looks like a highly magnified crystal, which when stacked forms a mineral called fluorite. It is not a form of fluoride but it is very pretty and comes in a variety of colors from clear to reds, blues, greens, yellows, etc..

Edit to say: It also looks like calcite, as both form a pyramid shape, but calcite forms a double pyramid(base to base). It also comes in a variety of colors.