How can I identify what type of rock I have?

Question

http://img136.imageshack.us/img136/4530/101417010ye0.jpg

I found this rock in 1984 in the western suburbs of Chicago. At the time I thought it was a fossilized egg, but I'm quite sure it isn't. It's consistently round and smooth all the way around; no bumps or dips -- just a few tiny knicks no bigger than what is pictured.
It looks similar to limestone, but I haven't been able to find another example of limestone that is as nicely rounded and with such fine grain texture. Can you offer any input on what you think it is, or perhaps some good resources to help me identify it. I've tried multiple search terms on Google and wasn't able to find much.

Answer 1

Could it be Quartzite?

Because of the smooth texture, I would assume that it's a very hard rock and has been warn smooth in like a river bed, beach or such.

Sandstone just isn't hard enough to stand up to that kind of abuse, but Quartize is metamorphic(exposed to extreme heat and pressure) sandstone and would look similar, but be very hard.

Anyway, hope that helps. It looks like a mighty cool rock.

Answer 2

I kinda feel bad for answering this question because I have no clue about rocks but...I looked at the picture and I do think it's a very pretty rock! Maybe besides a local university you could try an antique shop, I know they really don't deal much in rocks but they might could point you to a person that is knowledgeable in such things as 'strange' rocks!

Answer 3

Igneous : those rocks are quite solidified lava. As such, they have little if any grain shape and the greater sturdy types fracture like glass and function very sharp edges. Examples are obsidian and pumice. Metamorphic: those rocks tend to be floor sediments which get pushed below the crust. There, the warmth and rigidity of the mantle partly liquefies them. they preserve a lot of their grain shape, however the grains themselves are very tightly packed and fairly fused at the same time. Metamorphic rocks are additionally among the toughest of rocks because of the fact they have been compacted to such an volume. Metamorphic rocks incorporate granite and marble. Marble is what the sedimentary rock limestone will become after warmth and compression. Sedimentary : those are mineralized deposits of floor fabric, often the two sand, airborne dirt and dust or small shells and coral. this layer will become buried and compressed, yet to not the quantity that metamorphic rocks do. using this, sedimentary rocks have an fairly grainy shape and are the softest of rocks. Sedimentary rocks are the place maximum fossils are got here across. Limestone itself is rather a large fossil alongside with tens of millions of tiny shells of extinct marine organisms. besides limestone, there is shale which originated as airborne dirt and dust and sandstone which exchange into as quickly as sand. Sand itself is a mineral pronounced as quartz. that's almost organic silicon dioxide. Rocks are produced from numerous kinds of minerals. Geologists detect minerals and rocks in accordance to hardness and the colour of the streak they bypass away while scratched. different issues used are density. granite is amazingly dense, yet pumice is crammed with air areas and is a rock which rather floats.

Answer 4

If it fizzes in HCl, then its a carbonate.

It looks to be a very fine grained sandstone or quartzite. It is lightweight? If so maybe a well rounded chunk of pumice or tuff. But its hard to ID just from a pic. Take it to a local university's geology department.

Answer 5

the best way to clear ur doubts is by getting in touch with rock experts at the universy near u or any instituition around ur home town.
In my opinion it could be something worth a while coz of it's age, shape and texture.
Even if it's nothing at least u'd have found out the truth about it. Please let us know if u find any info about it.

Answer 6

get a piece of paper and the rock. Make a streak with the rock and go on the internet to look up different rock streaks. Then you can identify it. Have you tried wikipedia.com?

Answer 7

Join a ROCK & MINERAL club.
Go see one of these clubs and see fabulouse things.
My younger brother (two years ago) found the second most prized rock in the world. (took 2nd. in the worlds rock and mineral show in China)
Worth $140,000 .
These shows are amazing.

Answer 8

Oh that's pretty, I'd get in touch with a Geologist at some local university.

Answer 9

A local college or university.

Answer 10

from the picture it looks like smooth granite, but it most likely isn't, try a university or college, they might have someone to help you.