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Inclusa
2015-Jul-15, 05:09 AM
20783

One is multicolour, so this one will have different components.
Two look like dark chocolate and feature glossy, shiny "finish".
The other is black and has lines on it.

(Hint: These are river stones; I picked them up on a "beach"(?) on the river side.)

Squink
2015-Jul-15, 08:00 PM
The fracture planes on the middle one make me think chert/flint.

BigDon
2015-Jul-15, 09:18 PM
Inc,

What do they taste like ?

Trebuchet
2015-Jul-15, 11:27 PM
I just take if for granite.

geonuc
2015-Jul-16, 12:44 PM
Identification of rocks with such a small photograph is pretty difficult. A geologist would want to break the rocks to see non-weathered/abraded surfaces, which would expose the crystalline structure and get an idea of the mineral composition. Examination by hand lens would be preferable.

BigDon
2015-Jul-17, 04:15 PM
Did you click on the picture Geo?

I guessed three of them already and I have brain damage.

BigDon
2015-Jul-17, 04:18 PM
Clockwise from the red guy. The red one is granite. The top one flint/chert. Bottom one basalt.

The middle one I've seen a bunch of times but the name eludes me.

Jeff Root
2015-Jul-17, 07:01 PM
I saw the bottom one and immediately thought "basalt",
since I was just handling a similar, very perfectly-rounded
stone yesterday. No specific ideas about the others.

Squink apparently sees fracture planes in the middle
stone. I don't. I see concave eroded areas.

I suppose Don's question of what they taste like would
reveal iron if it is the source of the red color in the left,
middle, and possibly bottom stones.

-- Jeff, in Minneapolis

BigDon
2015-Jul-17, 07:06 PM
Or he could have been being a bit of a weenie. He's been know to do that on the rare occasion. Just ask Gillian.

Jeff Root
2015-Jul-17, 07:10 PM
The bottom stone actually looks very similar to some stone
meteorites I've seen and handled. Completely covered with
a fusion crust and then slightly weathered. Looks quite a bit
like basalt, at first glance.

-- Jeff, in Minneapolis

Jeff Root
2015-Jul-17, 07:16 PM
Ya know, the chances are one in a zillion, but that bottom
rock has a chance of actually being a meteorite. It would
probably have to be broken open to confirm it. An expert
could likely rule out the possibility without breaking it.

-- Jeff, in Minneapolis

BigDon
2015-Jul-17, 08:11 PM
What kind Jeff? I don't see it myself.

Jeff Root
2015-Jul-17, 09:42 PM
Some kind of stony meteorite. It looks very similar in shape,
color, and texture to some small stony meteorites that were
identified as such by experts. But they were not obviously
meteorites to my eye, and I don't know whether they were
suspected of being meteorites before they were broken open.
I certainly wouldn't be able to say that the stone in the photo
is a meteorite without breaking it open, and I doubt that an
expert could, either. I don't think I could rule out its being a
meteorite without breaking it open, while an expert probably
could.

-- Jeff, in Minneapolis

geonuc
2015-Jul-18, 10:27 AM
Did you click on the picture Geo?

I guessed three of them already and I have brain damage.

I did, yes. And with respect, your guesses are not founded on good evidence. Appearances of rocks in photographs can be quite deceiving, especially if they are weathered or eroded, as these ones are.

Inclusa
2015-Jul-20, 03:29 AM
I did, yes. And with respect, your guesses are not founded on good evidence. Appearances of rocks in photographs can be quite deceiving, especially if they are weathered or eroded, as these ones are.

These are river rocks, so weathering or erosion is inevitable here.

geonuc
2015-Jul-20, 12:14 PM
These are river rocks, so weathering or erosion is inevitable here.

Yes, I understand that.

I have many river rocks in my house, collected over the years, and even with close examination I can't always tell what they are without breaking them. And I have bachelors degree in geology.

For example, Big Don suggested the leftmost rock is granite. To my eye, it is not granite. There is too high a proportion of mafic minerals to be granite. But it may be granitic, a more general term encompassing a suite of rock types, including diorite, which is more mafic than granite. But it may also be garnet schist. The coloration is correct for that rock. Close examination of the specimen would easily distinguish between these two possibilities.

Knowing something of the field relations can provide clues, too. Knowing what rocks are found in the source mountains of the river will limit the possibilities.

BigDon
2015-Jul-21, 03:02 PM
I did, yes. And with respect, your guesses are not founded on good evidence. Appearances of rocks in photographs can be quite deceiving, especially if they are weathered or eroded, as these ones are.

Geo, I know my guesses were just based on camping trips. I was pointing out something about this board to a friend of mine.

The only reason I made a declarative statement is that after years on this board I know for a fact that declarative statements are always responded to by experts much more often than questions. I was proving this point to a person beside me at the time. I told him this would happen even as I typed it. Now I can call him and say it happened.


For example, Big Don suggested the leftmost rock is granite. To my eye, it is not granite. There is too high a proportion of mafic minerals to be granite. But it may be granitic, a more general term encompassing a suite of rock types, including diorite, which is more mafic than granite. But it may also be garnet schist. The coloration is correct for that rock. Close examination of the specimen would easily distinguish between these two possibilities.

Knowing something of the field relations can provide clues, too. Knowing what rocks are found in the source mountains of the river will limit the possibilities.

Had I not said what I did we would have never gotten the above information.

Everybody else. This method of extracting information from this board has to be used very carefully, else you can come across as a bit of a dink.

geonuc
2015-Jul-21, 06:25 PM
Geo, I know my guesses were just based on camping trips. I was pointing out something about this board to a friend of mine.

The only reason I made a declarative statement is that after years on this board I know for a fact that declarative statements are always responded to by experts much more often than questions. I was proving this point to a person beside me at the time. I told him this would happen even as I typed it. Now I can call him and say it happened.

Not quite, BD. I only responded because you all but called me an idiot for suggesting the rocks couldn't be identified from that one photograph. This statement:


Did you click on the picture Geo?

I guessed three of them already and I have brain damage.

Had you not posted that, I would have let my original statement stand.

Also, I'm not an expert and never have claimed to be one. I have some expertise in rock identification.

BigDon
2015-Jul-21, 06:29 PM
I didn't mean it that mean Geo. I was unthinking. I use that on the people on my side of the screen as a term of affection believe it or not.

Didn't even think about that part of the post that way until you showed me and seeing it now you have every right to be angry.

geonuc
2015-Jul-21, 06:34 PM
I didn't mean it that mean Geo. I was unthinking. I use that on the people on my side of the screen as a term of affection believe it or not.

Didn't even think about that part of the post that way until you showed me and seeing it now you have every right to be angry.

No worries, mate. We're good.