strange rock I found

Have found a strange rock/ crystal. Not sure if it is man made or natural. Found it on an old rock wall. It is harder than quartz and I have the pictures below any help would be great.


and another



Heres a larger picture

here's the other one

Well the second one in the pics but first linked I would say is flint. But the other pic suggests something like quartz.
I do like the 'bubbling' on the 'flint' side - never seen that before.

By the way this is just a guess, I had a look and to me looks like flint but I am quite ignorant regarding geology.

Nice looking stone either way and nice find

just looks like an agate to me.
especially the image of the opaque tanish color.
the bubbling occurs as the geode cools.
i'm interested in how you determined it being harder than quartz?

My great grandparents were lapidaries, and co-founders of our local Rock and Mineralogical Society.

This looks like quartz. Looks like a fragment of a geode to be honest. Definitely a cool find, but not super rare or anything. Can you tell us more about the location you found them at?

I could be wrong but this looks like something I've seen hundreds of.

I've seen rocks like that before!

Don't know how they're formed exactly... my neighbor is a geologist: Maybe I'll ask him.

Do any of your neighbors know about rocks? I bet at least one of them does. You should find out.

-R

reply to post by rubbertramp


Took a piece of quartz and it didn't scratch it. I thought it was wierd as most minerals dont form round crystals.
thought the roundness of the crystal was due to rapid cooling. A geode has geometric style crystals.

quarts not scratching it does not make it harder.
basically it means it is the same material.
it would take a harder mineral, like corundum to scratch it.

here, look through some of these links and i have a feeling you will see many samples that are very similar.

rock images

I found this which is similar :



The poster is suggesting it may be opal. Im not expert but i would have guessed it might be flint.

reply to post by PhoenixOD


flinkt, jasper, petrified wood, agate etc.....
are all basically the same material.

Originally posted by jlafleur02
Have found a strange rock/ crystal. Not sure if it is man made or natural. Found it on an old rock wall. It is harder than quartz and I have the pictures below any help would be great.

What you have there is a couple nice pieces of Chalcedony.... that formation is very typical of Chalcedony. Its not harder than quartz, but denser. Hardness 6-7. Agate would also be a correct term, but agate is more generic. Bedryodial chalcedony would be the correct term... and often times it is fluorescent under shortwave UV light

Chalcedony is a cryptocrystalline form of silica, composed of very fine intergrowths of the minerals quartz and moganite. Chalcedony has a waxy luster, and may be semitransparent or translucent. It can assume a wide range of colors, but those most commonly seen are white to gray, grayish-blue or a shade of brown ranging from pale to nearly black.

en.wikipedia.org...




The second piece...



Take it under a bright light or direct sunlight... if you see any flashes of color it might be good enough to be 'fire agate" hard to tell from that picture. If it shows opal like flashes it will have some value

reply to post by zorgon


I found this in mystic CT. Is this a natural occurence in this area?