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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6
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2answers
70 views

Curious natural patterns on the surface of basalt blocks that make up the sidewalk

During one of my walks through the city streets, I noticed that some basalt blocks that make up the sidewalk have in their surface some very curious natural patterns: The photos above was taken at ...
2
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0answers
24 views

What would create the triangles in this rock I found in the Lehigh River [closed]

I collect rocks from the Lehigh Valley River, I have found some many interesting rock. With details that could not be from the water. Can you tell me what would cause the 3 triangle indents on this ...
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0answers
62 views

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 ...
3
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1answer
32 views

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
52 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.
0
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1answer
44 views

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 ...
1
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1answer
31 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 ...
1
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2answers
58 views

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 ...
6
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2answers
113 views

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 ...
2
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0answers
57 views

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
95 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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0answers
61 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
95 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
125 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
56 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)
1
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1answer
82 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 ...
1
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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 ...
3
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1answer
822 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
97 views

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.
5
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1answer
118 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 ...
3
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0answers
66 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. ...
2
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0answers
86 views

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 ...
0
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1answer
113 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 ...
0
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1answer
61 views

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

What kind of rock is this?? Found laying on the surface of gravel.
3
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1answer
635 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 ...
5
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1answer
373 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 ...
0
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1answer
76 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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3answers
242 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
414 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.
2
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1answer
75 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?
7
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3answers
355 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 ...
5
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1answer
152 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 ...
2
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1answer
289 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
56 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 ...
0
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1answer
98 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
85 views

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?
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2answers
311 views

I found this strange spherical stone in Gillette Wyoming. I have no idea what it is. Please help. [closed]

These are recent pictures of it. It’s heavy, I see small minerals that catch the light in it, very bumpy, spherical, doesn’t seem to be magnetic, I was falling down a deep trench and kicked it up at ...
1
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1answer
79 views

What kind of purple stone is this? [closed]

I found this stone and I do not know what type of stone is this?
3
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1answer
312 views

heavy, brown, rock with crystals, please help identify [closed]

please help identify this rock. it is heavier than most. dark brown color. picture is shown with streak test. found in Philadelphia pa. at home demolition site. crystals seem to be different type and ...
3
votes
1answer
100 views

What kind of rock or stone is this? Where did it come from? [closed]

I found this on the side of the road in Oregon, i think it was left or forgoten about thats why it was left there but it has crystal pockets, multiple colors, some smooth sides, perfect circles and ...
1
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1answer
94 views

Glacial erratic - Granite or Gneiss? [closed]

This boulder is a glacial erratic in New Jersey. Can anyone tell if it's granite or gneiss? When you look at from the side, there appears to be foliation... but when you look at from the top or other ...
7
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4answers
743 views

How is this crumbly crystal-rich rock formed?

I found this crumbly rock embedded in the channel walls of a small creek in Everett, WA, USA. (North Creek that flows through McCollum Park.) If possible, I'd like to know how the rock formed... what ...
1
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1answer
743 views

What is this red rock with crystal white inside? [closed]

I found this rock in the desert. I found similar rocks that are crystal white on the inside, but this one is rough on the outside and all the others are smooth. Plus all the rough rocks doesn’t have a ...
0
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1answer
101 views

Can anyone help me identify this rock? [closed]

This is probably just something really common and boring to most people, but I was intrigued so I thought I might as well ask now I can. When I was in Portugal (I don’t know specifically where we were)...
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3answers
227 views

Can anyone help me identify these rocks please? [closed]

I apologize for any errors in my pictures or writing. My first post. [
2
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0answers
67 views

Whats this stone? [closed]

Found it couple days ago and it amazes me how smooth the surface is but cant identify it please help me. Found it in north germany near a lake on a trip there.
1
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1answer
128 views

Need help identifying this rock [closed]

I need a little help identifying this rock. It was found somewhere in the Sahara Desert. It is very hard and leaves a beige streak on a steel file (might be the concretized dirt covering it). The ...
0
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2answers
87 views

I believe we got this rock in the mountains of Creede Colorado [closed]

Solid, has some weight to it, looks like it possibly has some purple amethyst on the opposite side, but mostly consists of this silver: Can anyone identify it as silver?
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2answers
137 views

What type of yellow-green stone is this? [closed]

It's greenish yellow with white. Got it in a mixed stone package from Amazon. No luster, I'd say a 7 in hardness, it doesn't look homogeneous.
4
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1answer
75 views

Unidentified mineral found in France [closed]

(I am not a native english speaker, so I'm not really aware of the specific terminology.) A few years back, I found an unidentified rock on a beach in Normandie (France). It looks and feels (texture-...