Questions tagged [rocks]

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

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52 views

What is the "healthiest" rock?

When talking about rocks, i.e. an aggregate of minerals, which type would be the "healthiest" I'm not talking about some voodoo crystal-healing stuff here, just if there is any rock ...
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79 views

Igneous and Sedimentary Rocks' Susceptibility to landslide

Which is more susceptible to landslide based on lithology compared to one another? Granite, Conglomerate, Sandstone, Mudstone I've been tasked to create a hazard map and was given a Geologic Map, ...
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1answer
49 views

Internal rocks in glaciers

I am very new to the study of the cryosphere. I was looking at the GLIMS inventory for glaciers and observed red patches as shown below which the legend mentions the red patches as internal rocks. In ...
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1answer
21 views

Looking for Rock/Mineral Identification Flowchart

As a christmas present, I bought a box of minerals/rocks for my girlfriend, who recently got interested in geology. Unfortunately, she could not attend the identification class in university. The box ...
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2answers
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Why is felsic (granitic) lava so much more viscous when flowing (or trying to) than mafic (basaltic) lava?

A lower average temperature is, apparently, only part of the answer.... Several sites said composition, not temperature, explains most of the difference... And the difference in viscosity can be up to ...
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2answers
45 views

Why is the inner core about 85% iron and the rest (mostly) nickel, while the outer is roughly 80%/20%, if nickel is denser than iron?

As stated above.... I really cannot think of a good reason, on my own, why this should be so.... Is it a mystery to geologists?
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1answer
70 views

Where to find graphite rocks? [closed]

Where to find graphite rocks? I made researches in my city beach but I don't know where to find them.
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1answer
27 views

What is the sedimentary form of gabbro/diabase? What would it look like?

Gabbro is an intrusive, mafic, and igneous rock. How would it turn into sedimentary rock?
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1answer
556 views

Are there any rock recognition practices or games?

I'm a complete beginner in fossil collection but from my understanding I should mostly look at sedimentary rocks for fossils. However the problem is that rocks that I see in real life are not the same ...
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1answer
75 views

How did these holes form in the rock? [closed]

I've been trying to figure out how these holes formed in the rock. These pictures were taken in Quebec, Canada on small lake in cottage country. The strange thing is that they are almost both ...
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1answer
51 views

Does water affect radiometric dating?

When radiometric dating, would water affect the measured age of old rocks ? Specifically would water affect Uranium-238 to Lead-206 dating of Zircon crystals? Would it affect the lead since it’s ...
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1answer
86 views

Are we observing sedimentary rock formation today?

For instance, are we able to see the microscopic accumulation of shale or limestone? Can anyone reference me to sandstone formation observation, that would have to occur more rapidly. I’ve heard it ...
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2answers
151 views

What is this fossil found in flint in Kent?

My 7 year old son found this fossil whilst cracking open flint in Deal, Kent. The fossil (assuming it is) looks like scales/cells/shell and is chalky. The oblong lines are raised and well defined and ...
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0answers
74 views

What kind of rock is this? [closed]

A few years ago in Venezuela, parque nacional de Cainama, the tourist guide found and gave me this rocks, he told us that a geologist told him that those could be radioactive but no one believed him. ...
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1answer
152 views

How did this stone become encased within different rock?

My father, in his younger years, was a stone mason in Cincinnati Ohio. A couple of decades ago he was building a wall of some kind. He would fetch rock from a creek bed, haul it to the construction ...
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45 views

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 ...
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1answer
60 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
51 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. ...
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2answers
50 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
92 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
103 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
65 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 ...
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108 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 ...
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63 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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15 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
135 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 ...
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3answers
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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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28 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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2answers
129 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 ...
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3answers
134 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 ...
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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 ...
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48 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 ...
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1answer
77 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
591 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 ...
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1answer
57 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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36 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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4answers
91 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 ...
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1answer
327 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 ...
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1answer
110 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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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 ...
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1answer
74 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 ...
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2answers
257 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 ...
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2answers
88 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 ...
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0answers
29 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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442 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 ...
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1answer
43 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
50 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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1answer
73 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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2answers
95 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 ...
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3answers
591 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 ...