Questions tagged [rocks]

Questions about rock types, formation, chemistry, and physics.

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Is there a modelling of Wave Rock (Hyden Rock) formation?

I'm interested in the visualization of the formation process of "strange" objects like Wave Rock (flared slope). I've found articles describing hypotheses of the rock formation but I cannot ...
Charlie's user avatar
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When Earth formed 4.5 × 10⁹ years ago, how much radiation did surface rocks emit?

When Earth formed $\approx 4.5 \times 10^9$ years ago, Earth's surface rocks emitted more radiation because they had more unstable isotopes. All short half-life isotopes decayed long ago, and the ...
Châu's user avatar
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2 votes
1 answer
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What is the time period of these chalk/clay layers?

These limestone-clay rocks are very common in the Alps, they come from weather changes. How many years does it take to make one of the rock bands? 7 years, equivalent to an el-nino type event? 1000 ...
bandybabboon's user avatar
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7 votes
2 answers
643 views

Non-invasive techniques to find rock composition

If we had access to a totally new kind of rock (maybe a new meteorite), is it possible to tell what the rock is composed of without touching it / drilling into it? I'm thinking of something like ...
user1551817's user avatar
2 votes
1 answer
81 views

In radiometric isochron dating why is at t=0 D*/Dref=const but P/Dref not?

I am a physics graduate and trying to understand one of the assumptions made for isochron dating of rocks: at crystallization time of the rock, $t=0$, the ratio of the parent isotope to a stable ...
NeStack's user avatar
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42 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 ...
Michael Walsby's user avatar
5 votes
4 answers
135 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 ...
Ergative Man's user avatar
4 votes
1 answer
368 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 ...
zsh_18's user avatar
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3 votes
1 answer
204 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 ...
Lakhwinder Sidhu's user avatar
3 votes
0 answers
28 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 ...
akkab's user avatar
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4 votes
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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 ...
Somto's user avatar
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4 votes
2 answers
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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 ...
Volker Siegel's user avatar
6 votes
2 answers
115 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 ...
Lacobus's user avatar
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2 votes
0 answers
49 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 ...
Natalie's user avatar
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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 ...
Linda Cash's user avatar
3 votes
1 answer
55 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,...
Marlon Calispa's user avatar
1 vote
1 answer
51 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 ...
Sanskros's user avatar
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1 vote
1 answer
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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 ...
Charitoo's user avatar
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1 vote
2 answers
263 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 ...
Zam's user avatar
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9 votes
3 answers
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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 ...
Owen Versteeg's user avatar
2 votes
1 answer
61 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 ...
user avatar
3 votes
1 answer
3k 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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5 votes
1 answer
438 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 ...
Mohammad Nayef's user avatar
3 votes
1 answer
2k 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 ...
Karl's user avatar
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5 votes
3 answers
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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 ...
Cory Klein's user avatar
9 votes
3 answers
2k 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 ...
Treblig's user avatar
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1 vote
0 answers
369 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 ...
Lance's user avatar
  • 269
0 votes
1 answer
145 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 ...
Michelle Tillitson's user avatar
3 votes
2 answers
956 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 ...
Sidney's user avatar
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0 votes
1 answer
320 views

What kind of purple stone is this? [closed]

I found this stone and I do not know what type of stone is this?
Wakil Rahimi's user avatar
3 votes
1 answer
335 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 ...
Olivia Dick's user avatar
7 votes
4 answers
3k 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 ...
BMS's user avatar
  • 223
0 votes
2 answers
1k 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.
Cheyenne's user avatar
3 votes
1 answer
381 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 ...
settler's user avatar
  • 31
0 votes
1 answer
82 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.
PROBERT's user avatar
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5 votes
1 answer
243 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. ...
Yaboy33's user avatar
  • 83
3 votes
1 answer
612 views

Differentiate a rock and mineral

How to differentiate between a rock and a mineral by merely looking at it as a thumb rule?
gateprep's user avatar
1 vote
0 answers
374 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:
Herb's user avatar
  • 11
2 votes
3 answers
1k 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 ...
Faraz Gerrard Jamal's user avatar
1 vote
1 answer
560 views

How can I tell the difference between granite and syenite?

(I'm not a geologist, just helping my kids collect rocks).
Lars Nygaard's user avatar
1 vote
1 answer
2k views

Is this platinum ore? [closed]

Was found in central Mexico. It's very metallic, shiny, showing some streaks of gold and quartz.
hondo3265's user avatar
4 votes
0 answers
372 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 ...
throwaway0555585's user avatar
2 votes
1 answer
649 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 ...
Porcupine's user avatar
  • 647
1 vote
1 answer
1k views

Oldest to Newest Bedrock in the USA "road trip"

I am supposed to design a road trip (using major highways) across North America. I have to design a route that starts with the oldest rock of Archean age and finishes with the youngest rock of ...
Alexander H. R.'s user avatar
3 votes
2 answers
2k views

Radon is a naturally occurring radioactive gas. How does this work?

Radioactive rocks can release a gas called radon when they decay, which can build up in the basements of buildings with serious effects on people's health. Does anybody have information on how radon ...
Jeffrey Boettger's user avatar
16 votes
0 answers
3k views

What is the global distribution of oil filled geodes?

In a general 40 mile radius of Keokuk, Iowa many sedimentary geodes can be found. They are abundant in the Warsaw Formation with the type section at Geode Glenn in Warsaw, Illinois. In one specific ...
user avatar
1 vote
0 answers
80 views

I was wondering if anyone could help me identify this rock [closed]

I found this rock along with a few other very similar ones. I found it on an island in Croatia.I was wondering if anyone could tell me the name of the rock.
M.Mar's user avatar
  • 11
1 vote
4 answers
672 views

What is this Lake Michigan rock? [closed]

Rock found along northern Lake Michigan, (Charlevoix, MI). Made up of very thin crystalline layers. There are small, round bubble like bumps that protrude from the surface. Doesn't show well in the ...
BR in MI's user avatar
3 votes
5 answers
1k views

Where are the oldest igneous rocks found?

I'm trying to catch up on my homework for earth science, but I'm having a difficult time searching for an answer to my question.
Kitty's user avatar
  • 31
0 votes
1 answer
218 views

What is the definition of "ground-up shell"?

The archeologists use the term "ground-up shell" to designate a type of temper used for pottery. What is this material? Earth containing fossilized mollusk shells? I noticed the term is also used in ...
Fructibus's user avatar
  • 101