Questions tagged [rocks]

Questions about rock types, formation, chemistry, and physics. If you just want help identifying a rock please use the tag "identification-request".

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0answers
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How can I find out if this is a geode without breaking it in half? [closed]

I found this rock today on my property. It looks similar to another rock I saw that was said to be a civil war cannon ball, however comments below suggest that it could be a geode. Are there any ...
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1answer
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Marks on boulders of volcanic origin

I am working in a catchment in the southern Ecuadorian Andes, about 3700 m.a.sl. Rock outcrops at the upper part of the catchment, as massive blocks varying their size from one meter up to five meters,...
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1answer
63 views

What kind of rock is this? (Sedimentary) [closed]

This rock was obtained from a nearby quarrying from our grandparents' house on an island. It has a couple of bronze/mud colored linings on it and a bunch of scattered white areas. Could also see tiny ...
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1answer
48 views

Hi please could someone help identify this rock. Received it as a gift from a friend [closed]

The rock has green,purple and white stripes.
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1answer
128 views

Help to Identify a Rock Found in Gray Clay [closed]

Found digging a pond. The rock was inside Gray Clay 18 feet below grade. The person who gave it to me tried cutting it with a grinder. This left an area that looks like steel. Location: ...
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1answer
135 views

I found this stone with metal linings can someone identify it? [on hold]

I am more curious about the metal on the surface (if it's even metal?) on this stone :) I don't really remember where I found it, probably at this beach of the Baltic Sea, but there is also a chance ...
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1answer
73 views

Rock ID: black rock found in Central Europe [closed]

I'm note sure if it's an anthracite, augite, jet (lignite) or something completely different. I don't know where exactly i found it because it's from my old rock collection. I would appreciate your ...
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1answer
45 views

What types of rocks are these [closed]

I can’t figure out what type of rocks these are I would like to create pigment out of them to make a watercolor want to make sure they are safe, one is brick red the other is more of a deep magenta, ...
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1answer
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If gypsum turns into plaster around 210 F, is there any natural plaster deposits or formations out there?

For a while I have been working with gypsum I mined from a site in Utah, and I realized how low the temperature is to turn it into plaster, so I was wandering; has there ever been any cases of large ...
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2answers
69 views

What type of rock is this [closed]

![I found the the rocks is Eastern Arizona by the Black Mesas. They are white with a few orange patches. The inside kind of looks like quarts.
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1answer
27 views

How to calculate or find the compressional stress wave velocity, Cp for a rock

In Cunningham's paper, "The Kuz-Ram fragmentation model - 20 years on", he makes mention of compressional stress wave velocity, Cp. He only comments that the Cp of granite = 5.2 km/s. I using a ...
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3answers
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Pinkish rock with red 'veins' [closed]

I found this rock in Smithfield NC. It does scratch glass. A butter knife didn’t scratch it. When you hold it to a light it has an orange glow. It didn’t leave anything on porcelain.
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Chloride ions for the salty seawater

Where does the chloride ions that are required for the salty taste of sea water come from ? I know that it is the weathering caused by the slightly acidic (due to dissolution of CO2 with water) rain ...
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1answer
301 views

Is this rock Massive Epidote? [closed]

enter image description here This is a close up of outside of chipped off piece, and inside alsoI found this rock in Co. Donegal Ireland on a river bank buired under the dirt. It weighs 16.4lbs- 7....
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2answers
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Is there a widely accepted reason for the formation of tafoni?

Expansion of tafoni seems to be based on weathering (seems reasonable enough.) But what creates them in the first place? There are a number of explanations online (Wikipedia lists eight plausible ...
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Is it an egg? What type of rock please? [closed]

This stone was found by my uncle in Western Queensland. It’s light brown in colour and smooth. It's very heavy for its size. 780 grams. Pocket knife doesn’t scratch it. many thanks.
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1answer
83 views

Help me identify my rock is it jade? [closed]

Found this rock it looks like a vein of Jade but I have no idea. This is the inside of the rock. I found it already broke the rock is wet in the pic. It's is a hard rough texture and the green in the ...
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51 views

what type of rock is this? blue/green and brown [closed]

I found this rock while up in the mountains and I have no idea what type of rock it is.
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2answers
91 views

Can someone help ID this rock [closed]

Found today in a creek in Indiana, has a geode look and the broken edge shows red opaque facades.
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1answer
121 views

Identification required, rock formation found whilst on holiday in Cephalonia, Greece white object embedded inside? [closed]

This rock was found in kephalonia Greece, on a beach in lassi. The rock is black in colour, smooth with thumb like prints, very metallic smell and very slightly magnetic. We took this rock to oxford ...
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1answer
500 views

Identification of a rock from Kentucky [closed]

I was hiking the other day in southeastern Kentucky and ran across this rock on a river bank. I've never seen a rock like this before. Can anyone here identify it?
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1answer
49 views

Anyone have any idea what these are? [closed]

Can someone please help me identify these rocks please ](https://i.stack.imgur.com/y28zy.jpg)
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1answer
70 views

Help me to identify this strange rock [closed]

About 9 years ago I found this rock in the middle of the river. It reminds me of a some kind of a volcanic rock, but I live in Finland, and we only have dead volcanoes around here. Outer layer is just ...
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1answer
125 views

Can anyone help me identify this rock found in Tulsa Oklahoma? [closed]

I was working in my front yard in Tulsa Oklahoma and ran over this rock with my lawnmower. It was logged in the ground enough I didn’t see it. It’s 2.5 inches in length. Black in color with what ...
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1answer
26 views

Why don't pyroxenites and peridotites appear in Streckeisen's QAPF diagram?

Wikipedia says for QAPF diagrams: "A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition." Why don't pyroxenites and peridotites ...
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1answer
413 views

What's the difference between cleavage and fracture?

I see both terms refereing to fractures on crystals or minerals, so I wonder if they could be considered synonymous. If no, what's the difference between both terms?
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2answers
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Can anyone identify this stone [closed]

i found this stone on the east coast of south island in New Zealand, it's 200 grams and very hard,i used a metal file on it and it left steel residue on the stone.
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1answer
77 views

rock id:hard,green,other ones were around but not with black streaks [closed]

Located in vermilion river Lasalle Il. It is a green and has black streaks with what looks like air bubbles at the end.
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1answer
449 views

Can someone please help me identify my rock? [closed]

Hey guys! My name is Brent and I found this rock over 20 years ago while swimming with my siblings in Lake Huron near Kincardine, Ontario. I actually found it under water at one of our favourite ...
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1answer
97 views

Identification of limestone type

These are images of a stone found and used extensively in the Jammu & Kashmir region between India and Pakistan. These are called devir or devri in the local parlance. Following is the ...
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0answers
63 views

What is in this rock? [closed]

There were many, many examples of this, my photo simply shows a situation where I had even light and time to take a photo without making anyone wait for me. The basic rock is obviously sandstone. ...
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0answers
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Identify rock found on beach in Florida [closed]

This rock was found in Florida on the beach on top of the sand. There were no others found. Color of rock is white, the outer rim is clear (see through) the inner layer is solid. The inner layer is ...
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1answer
76 views

Identify rock, found in Florida [closed]

Round with crystal looking around it, hard. Seems to have layers in the center. The inside is smooth and the outside layer is textured. The white layers go all the way through the rock. Found on the ...
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1answer
56 views

What kind of rock is this?? White rock [closed]

What kind of rock is this?? Found laying on the surface of gravel.
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1answer
452 views

What is the difference between subvolcanic rocks and plutonic rocks?

I'm studying Plutonic (Intrusive) rocks and I really don't understand the difference between Plutonic Rocks that form in Sills and Dikes from the so called subvolcanic rocks, also known as a ...
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1answer
77 views

Mineral/rock identification [closed]

I found this rock in the Himalayan region in India. It was on the roadside of a hill that we were trekking. It has a silver lustre. It has a hardness of 5.5(I can scratch it with a knife blade).it has ...
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1answer
367 views

Please Help Identify My Rock [closed]

This rock is smooth, heavy and dark grey/black in color with white blotches which are different in shape and size and are also porous. It scratches by a knife and I found it in with many pails of ...
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0answers
166 views

Rock ID: black, white and orange, from Malaga, Spain [closed]

I picked up some very interesting rocks and pebbles on the beach in Malaga, Spain this summer. They are predominately flat and colored dark grey crisscrossed with stripes of orange and white. The dark ...
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1answer
365 views

What is this yellow stone [closed]

I found this yellow stone in a creek.It was easy to break by slamming it against another stone and has evenly spaced crystal clear grains.They are very clear that under the sun I thought that water ...
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1answer
62 views

What is this stone or mineral it's light but strong [closed]

The other side is just cyan color I don't know where this stone is from Any help is appreciated
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1answer
59 views

What is this translucent blue-green oblong crystal? [closed]

I think it might be aventurine of some sort, but I'm not sure. Hardness: It is harder than a steel nail file. The file leaves a track, but it rubs off, leaving no mark. I scraped it on the bottom ...
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3answers
222 views

Making a local geological field trip an interesting and educational event for children?

I have no expertise in geology or earth science, but I would like to do a "field trip" with my home-schooled young children (under age 10) where I could teach them about geology from a hands-on ...
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1answer
305 views

Rock identification: gray with small dark lines/inclusions all over [closed]

Gray stones with short small dark shiny lines all over it. Found it on the beaches of Newport Rhode Island.
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1answer
70 views

What is this figurine made of: [closed]

Have several of these animal figurines, MADE IN USSR on bottom. Can't figure out what type of rock it is made from. Any ideas?
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3answers
335 views

Could one say that granites are metamorphic rocks, or not at all?

In my old textbooks, granites used to be part of the metamorphic rocks. Is this still true or not ? If not fully true, to which extent ? Could someone point me towards clear examples or definitions ...
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1answer
139 views

Identification: mystery rock with golden features and shimmer [closed]

I found this rock in our backyard in Germany. As our garden is filled with bushes it was very oddly placed and I have carried this rock around with me ever since, wondering what sort of rock it might ...
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1answer
259 views

Help Identifying this rock with a rainbow [closed]

I found this rock and I want to know what it is. It looks like green-grey and when I put one side of the rock on the sun, it changes its colors on that side. Thanks
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0answers
49 views

What a place that sells rocks is called [closed]

If a nursery sells plants, I'm wondering what a place that sells rocks is called. Something where they offer rocks of various sizes like this: Well, those are all river rocks, but I'm wondering about ...
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1answer
91 views

I need help with these geode like rocks [closed]

I found these rocks in my pasture and was excited because I thought I had found some geodes. The rocks were in a sandy bank and looked like eggs sticking out of the bank. I am located in Ness County ...
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2answers
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Can someone help me to i identify this rock found in macedonia [closed]

Can someone help me identify this rock? Also, will it react to acid?