Questions tagged [rocks]
Questions about rock types, formation, chemistry, and physics.
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Prevalence of 'well-rounded' beach fabric on the Foreshore
Apologies for the vagueness of this query, but generally, would it be plausible to state that the prevalence of 'sub-rounded'* beach fabric is more common at the foreshore than 'sub-angular'* beach ...
2
votes
1answer
33 views
How to identify chemical property and structure of rocks?
I am interested in identifying the properties of rocks. For example, black opal is shiny and can emit 5 different colors based on different lighting conditions. Is there a way for an amateur to be ...
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1answer
45 views
Ore Deposit Identification
What type of ore deposit does this rock best represent?
A rock with a porphyritic texture is cross cut by a stockwork of
quartz veins. Bordering the veins is extensive alteration of the host
rock. ...
3
votes
2answers
36 views
Feldspar content of coarse-grained igneous rocks
From the chart, I would say that plagioclase feldspar is more abundant in coarse-grained igneous rocks than alkali feldspar, as it is found in all three listed, whereas alkali feldspar is only present ...
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1answer
60 views
Arabian Desert rock formation
I'm interested about this rock formation in Arabian desert. The rock looks like melting chocolate.
Not sure where the exact Location, the source says it around Al-Ula, Saudi Arabia. Here the image ...
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4answers
89 views
How is it possible for rocks to be trapped within another type of rock?
More specifically, I would like to know how the rocks in these pictures have formed:
If this is because magma has melted and trapped the other rocks inside, do they have a different melting point ...
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1answer
39 views
What causes dye to bleed from an agate stone?
I came across this review on Amazon. The cold drink was placed on top of the agate stone and the dye bled and left a permanent mark on the table.
Why does this happen? Is it because of the ...
4
votes
0answers
95 views
What's eating this sandstone
I decided to remove the tiles in my front courtyard and turn it into a garden of succulents. After removing a couple of rows of tiles then digging into the soil, I started seeing a strange thick ...
3
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0answers
58 views
How would one go about drawing the contour lines for this map in order to draw the cross section?
Good Day. We Received this map as practice for our Geology university module and I have no idea how to draw the strike lines where the different heights intersect the different rock types in order to ...
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0answers
12 views
Lamé parameters of granite and similar rocks
I am looking for a book or an article where I can find the Lamé parameters of Granite, any help would be appreciated.
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1answer
35 views
What is this red glassy rock [closed]
I found rocks looking like this in my backyard but cant get to know what they are or how to find out. Below are pictures
I don’t know if there’s more info I should mention. If there’s anything please ...
5
votes
3answers
92 views
Why does radioactive dating work on specific rocks?
As I understand it, radioactive dating measures time by what portion of a radioactive isotope has decayed. Weren't all the natural radioactive isotopes created during the formation of the solar system?...
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0answers
25 views
Megaspherulite growth
I have been fascinated by photos of these for a while, and I would like to ask how megaspherulites grow so large, when spherulites are normally quite small?
I also noticed that all papers about the ...
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vote
2answers
110 views
Why aren't there ultra acid igneous rocks?
In my study, I found that in volcanoes when the magma is going up it formed different types of rocks. There are basic, acidic and ultrabasic.
My question is why isn't there ultra acid igneous rocks ...
2
votes
3answers
124 views
Using Enhanced Rock Weathering in the Sahel Region of Africa
A recent Guardian article "Spreading rock dust on fields could remove vast amounts of CO2 from air" has gotten some attention in the nongovernmental and UN organizations working in the Sahel ...
2
votes
0answers
53 views
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 ...
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0answers
47 views
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 ...
2
votes
1answer
74 views
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 ...
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2answers
574 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 ...
2
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1answer
43 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 ...
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0answers
50 views
Estimations of time to turn a beach rock into this?
[ROUND BEACH STONECan anyone help determine how long it would have taken to turn this rock into the ball it is now? heavy density .Found on the South Coast here in the UK near Lyme Regis (Jurassic ...
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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 ...
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votes
4answers
85 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
303 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
79 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 ...
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votes
0answers
26 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
66 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
183 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
85 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
...
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0answers
162 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
37 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
69 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
48 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 ...
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vote
1answer
48 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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vote
2answers
64 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
398 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 ...
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1answer
30 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
2k 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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votes
1answer
206 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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1answer
134 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
1k 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
275 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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votes
3answers
428 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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0answers
135 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
120 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
478 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 ...
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1answer
149 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
207 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
1k 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 ...
