# Can you identify this rock? **URL:** \ **Category:** Factual Questions\ **Created:** [August 7, 2012, 11:28pm UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800 "2012-08-07T23:28:25Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [August 7, 2012, 11:28pm UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/1 "2012-08-07T23:28:25Z")
[Mystery Red Rock](http://www.facebook.com/media/set/?set=a.4351777910476.2182749.1168490711&type=3) The link is to pictures of pretty rock that my daughter found outside. It’s color is actually more of a maroon, but it doesn’t appear that way using my digital cameras. I thought it might be jasper, but it’s not quite dense enough (1.5-1.6 kg/l as opposed to 2.5-2.6 for jasper). Any geologists (pro/am) have an idea what it could be? ---
**Author:** ![ArmenE](https://avatars.discourse-cdn.com/v4/letter/a/e9bcb4/32.png) [@ArmenE](https://boards.straightdope.com/u/ArmenE)\ **Post date:** [August 7, 2012, 11:30pm UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/2 "2012-08-07T23:30:42Z")
> [@AWB](#): > > [Mystery Red Rock](http://www.facebook.com/media/set/?set=a.4351777910476.2182749.1168490711&type=3) > > The link is to pictures of pretty rock that my daughter found outside. It’s color is actually more of a maroon, but it doesn’t appear that way using my digital cameras. I thought it might be jasper, but it’s not quite dense enough (1.5-1.6 kg/l as opposed to 2.5-2.6 for jasper). Any geologists (pro/am) have an idea what it could be? Note that you have to be logged onto facebook to view this. I have no idea what it is though. It looks like a bean. ---
**Author:** ![TriPolar](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/tripolar/32/3008_2.png) [@TriPolar](https://boards.straightdope.com/u/TriPolar)\ **Post date:** [August 7, 2012, 11:36pm UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/3 "2012-08-07T23:36:28Z")
Where it was found might be useful information. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [August 8, 2012, 12:01am UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/4 "2012-08-08T00:01:39Z")
Some better focused photos might be useful, but it looks like a very well-rounded river cobble of some sort, which are usually pretty difficult to identify without cracking them open for a fresh exposure that you can see some texture in. ---
**Author:** ![the\_diego](https://avatars.discourse-cdn.com/v4/letter/t/7bcc69/32.png) [@the\_diego](https://boards.straightdope.com/u/the_diego)\ **Post date:** [August 8, 2012, 12:03am UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/5 "2012-08-08T00:03:45Z")
Dang, what a challenge. It’s too rounded and smooth (transported) and maybe oxidized to give one a diagnostic texture and color. Yes, note the place whence it came. For now, don’t scratch or break it or drop any chemical on it until a qualified earth scientist looks at it. If it’s a small piece, it’ll be harder to identify without breaking it up. ---
**Author:** ![Arkcon](https://avatars.discourse-cdn.com/v4/letter/a/96bed5/32.png) [@Arkcon](https://boards.straightdope.com/u/Arkcon)\ **Post date:** [August 8, 2012, 12:29am UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/6 "2012-08-08T00:29:04Z")
When trying to identify a rock, it can help to use some things other than color. See if it gives a very different color streak – that is, scratched along unglazed white tile to see the color of the powdered rock. Try the see what rocks its harder than, and what rocks are softer than it. Specific gravity is a little tough, but if it is much heavier or lighter than similar sized rocks, you can use that info to help you narrow down identity. ---
**Author:** ![AWB](https://avatars.discourse-cdn.com/v4/letter/a/bb73d2/32.png) [@AWB](https://boards.straightdope.com/u/AWB)\ **Post date:** [August 8, 2012, 12:34am UTC](https://boards.straightdope.com/t/can-you-identify-this-rock/630800/7 "2012-08-08T00:34:01Z")
It was found in San Antonio, TX. It has sedimentary layering, but it might well be metamorphic. The red definitely looks like some iron presence.