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".
169
questions
6
votes
2answers
78 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
votes
0answers
25 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
...
1
vote
0answers
69 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
votes
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,...
-1
votes
1answer
56 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
votes
1answer
45 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
vote
1answer
34 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
vote
2answers
59 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 ...
7
votes
3answers
168 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 ...
1
vote
1answer
95 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
vote
1answer
27 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
votes
1answer
971 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?
1
vote
2answers
120 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
votes
1answer
131 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
votes
0answers
67 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
votes
0answers
91 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
votes
1answer
122 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
votes
1answer
63 views
What kind of rock is this?? White rock [closed]
What kind of rock is this?? Found laying on the surface of gravel.
3
votes
1answer
709 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
votes
1answer
375 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
votes
1answer
85 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
5
votes
3answers
256 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 ...
0
votes
1answer
461 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
votes
1answer
76 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
votes
3answers
361 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
votes
1answer
163 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
votes
1answer
301 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
1
vote
0answers
59 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
votes
1answer
105 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 ...
1
vote
2answers
87 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?
3
votes
2answers
337 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
vote
1answer
87 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
votes
1answer
332 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
125 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
vote
1answer
96 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
votes
4answers
806 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
vote
1answer
842 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 ...
1
vote
3answers
252 views
Can anyone help me identify these rocks please? [closed]
I apologize for any errors in my pictures or writing. My first post.
[
2
votes
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
vote
1answer
129 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
votes
2answers
104 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?
0
votes
2answers
147 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
votes
1answer
78 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-...
3
votes
1answer
137 views
How does this melted-wax erosion pattern form in sandstone?
How does this kind of erosion pattern that looks like melting wax form in sandstone? Can you describe the kinds of processes and kinds of rocks that are needed for this? I've seen it in Nevada, but ...
0
votes
1answer
90 views
Identify this transparent brown rock [closed]
t
The rocks are pretty small they are dark brown and comoleyelybsee through.
1
vote
0answers
54 views
Identifying rocks, minerals [closed]
I am sorry to bother you.. before passing away, my grandfather gave me a special box that contained all types of beautiful, colorful rocks and minerals. I am having a hard time identifying them! Could ...
1
vote
0answers
66 views
Rock / Fossil ID? [closed]
Please see link below if anyone can help ID.
I think the little claw looking thing is a fossil?
The red rock is smooth,Matt in some places and semi glossy on some of the sides.
The black rock has ...
0
votes
1answer
47 views
Rock identification ? What kind of it is? [closed]
My co-worker had this rock and told me found just behind the store, Big R, and put on the table in the office.
Location is Trindad, Colorado.
2
votes
2answers
91 views
Need help to ID rock type [closed]
I found this rock in a freshly ploughed field, and it looked too unusual to pass up. Can anyone identify what it is?
4
votes
1answer
190 views
Why would CaO be more finely spread than K2O in Granodiorite?
I recently interpreted some XRF data on samples of a granodiorite which were classified under three different types of physical characteristics: very little, mild and significant levels of weathering. ...
