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".

Filter by
Sorted by
Tagged with
2
votes
0answers
34 views

Use of radiolarian fossils to assess CO2 levels in early geological periods

Radiolaria are microscopic marine protozoans commonly found as fossils in rocks dating as far back as the early Cambrian. Their silica skeletons are damaged by high levels of CO2, so is it possible to ...
5
votes
4answers
69 views

Sources or strategies for stone identification

I have a bunch of semi-precious stones here, but I am not very learned in geology etc and I would like to have some way to know what kind of stones they are. As far as I understand question about ...
5
votes
1answer
288 views

Spatial Continuity in python

I have data like this of rocks from 3 blast holes: These are the rock properties of each blast hole of a mining site. The rock properties come from the Block model of that mining site. I want to ...
3
votes
1answer
74 views

What ore minerals are likely to be found in a thin section like this? What can we deduce from the structure?

The following image is of polished sample of mineral-rich rock. There are two major portions we can see that is ore minerals and rest the grayish material is gangue. The photo was taken with an ore ...
2
votes
0answers
25 views

Faster shale velocities in deviated wells

I am currently working with sonic measurements in the wells and there is an observation, that velocities are faster in shales over the deviated parts of the well. So, when the relative dip between the ...
3
votes
1answer
61 views

Energy Density of Porous Rocks

It's very long, I know. But please, don't be discouraged from going through this question if you can help me. The question is at the second to the last paragraph, but you need to read through to ...
4
votes
2answers
179 views

Why are metals so separated in the Earths crust? [duplicate]

I find it very surprising that metal ore deposits are so separate, and unevenly separated on the Earth. I do understand that there were various different conditions at some point in time in the ...
6
votes
2answers
81 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
26 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
75 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
33 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
60 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
47 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
35 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
60 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
231 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
28 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
1k 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?
5
votes
1answer
149 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 ...
0
votes
1answer
65 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
850 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
3answers
263 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 ...
7
votes
3answers
389 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 ...
2
votes
1answer
330 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
70 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
109 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 ...
3
votes
2answers
353 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
93 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
354 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
146 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 ...
7
votes
4answers
905 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
3answers
288 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
70 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.
0
votes
2answers
173 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
88 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
149 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 ...
1
vote
0answers
56 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
68 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
49 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.
4
votes
1answer
193 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. ...
1
vote
1answer
59 views

Help identifying rock? [closed]

Found in stream, heavy, has a tin of red lines and dark. 1]]2[grey white, rusty ]3. Dark lines n rusty lines. Hard to break off piece ain't magnetic
3
votes
1answer
199 views

Differentiate a rock and mineral

How to differentiate between a rock and a mineral by merely looking at it as a thumb rule?
1
vote
0answers
93 views

I found this rock on Laguna Beach [closed]

Rock found on Laguna Beach. It is not sand stone and is heavy for its size 3" x 2". It is rather dense. Click the image for full size:
2
votes
3answers
680 views

What is meant by intraplate volcanism?

I am having massive confusion on whether intraplate volcanism refers to volcanism occurring at plate boundaries or away from plate boundaries (such as formation of ocean island basalts), or perhaps ...
1
vote
1answer
229 views

How can I tell the difference between granite and syenite?

(I'm not a geologist, just helping my kids collect rocks).
2
votes
2answers
2k views

What is the identity of this heavy, smooth, shiny black and red rock? [closed]

. It's very shiny and layered. It has rough texture but spots with smooth red colored pieces.
1
vote
1answer
1k views

Is this platinum ore? [closed]

Was found in central Mexico. It's very metallic, shiny, showing some streaks of gold and quartz.
3
votes
2answers
884 views

What is this white rock with black speckles throughout? [closed]

I was wondering if you have any ideas on what kind of rock this might be? I know that it doesn't effervesce with HCl (no reaction with hydrochloric acid at all) and the size and shape of each grain is ...
3
votes
0answers
319 views

Puzzle using relative dating principles

This isn't directly looking at a real life ecological example kind of thing, but it requires knowledge of relative dating, so I thought I would come here. Here is what was told: -"Worms" (curved ...
2
votes
1answer
431 views

Inorganic Limestone and Inorganic Gypsum

I read that limestone is made from the compaction of marine animals' bones. But, I am unable to find out why limestone could not have been produced from calcium occurring naturally (5th most abundant ...