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Questions tagged [geology]

The science comprising the study of the rocks Earth is composed of, and the processes by which they change. Some subfields of geology are petrology, mineralogy, and geophysics.

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Can someone tell me what this stone is?

My father found it in the Himalayas 20 years ago. It was unique looking stone in a rock-fall. It is 6-7cm in diameter, well rounded. It has dark almost black outer stone-like layer and metal center. ...
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I have found this while walking dog can you please help identify it [on hold]

i found this while walking dog it’s very heavy for its size and itsa about 35mm by 25mm by 20mm
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Please help me identify this stone? [on hold]

Please help me identify this stone
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What structure of fossil plants can be measured by scientists to estimate the $CO_2$ in the earth’s atmosphere prior to a million of years ago? [closed]

Why is this feature of plants a good way of estimating how much $CO_2$ was in the Earth’s atmosphere?
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Undergraduate Geology to Atmospheric Science

I am curious as to the possibility of transitioning to Atmospheric Sciences in Graduate study after obtaining a bachelors in geology. I am studying geology, but will have the equivalent of a minor in ...
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1answer
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Could this rock be Basalt?

This rock is 2 3/8", weighs 71 grams has a density of 2.958,I tested the density a few times and its always 2.958, has a hardness of 6-7 almost clear streak test, I tested the streak again and I would ...
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3answers
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Would oceans regenerate if removed?

On Earth, there is enough Hydrogen and Oxygen to make 13,88 million km$^3$ of water (calculation below). However, oceans contain only a tenth of that. Clearly, most of the hydrogen must be stored in ...
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1answer
130 views

What is this green yellow heavy stone?

no known origin,its opaque its 2 1/4" leaves no streak, has a hardness of 6-6 1/2 I drilled it with a diamond plated bit,it is a very tough stone.It weighs 2ozs 56.6 grams.When I drilled it the powder ...
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1answer
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What kind of lava tube feature is Cleopatra's Grave?

Cleopatra's Grave is a natural feature inside (warning: PDF) Catacombs Cave in Lava Beds National Monument near Modoc, California. Source: LookBeforeYouLive My apologies, as this image is somehow in ...
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1answer
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Help identify my redbrown rock with crystal like formation on the inside

This rock is red/orange/brown in color. It is slightly clear/translucent when held up to light. Will not scratch with a knife. Has a crystal like structure on the inside.
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1answer
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What is the difference between subvolcanic rocks and plutonic rocks?

I'm studying Plutonic (Intrusive) rocks and i really dont understand the difference between PLutonic Rocks that form in Sills and Dikes from the so called subvolcanic rocks, also known as a ...
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Earth age by meteorite dating [duplicate]

Why we use meteorites to calculate Earth's age? What makes meteorites so special for that process?
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Why the mineral composition of most sills/dikes is basaltic?

I'm studying from the Tarbuck-Lutgens, and in the dikes & sills section (chapter 4) it says that they are product of very fluid magmas, meaning that they are low silicate. I dont get how this ...
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1answer
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Please Help Identify My Rock

This rock is smooth, heavy and dark grey/black in color with white blotches which are different in shape and size and are also porous. It scratches by a knife and I found it in with many pails of ...
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1answer
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How do you tell if smoky quartz has been irradiated?

I want to purchase a piece of smoky quartz crystal, but am not sure if it is irradiated. Is there a way to tell if it has been irradiated? Thank you.
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1answer
70 views

Can someone identify this mineral? [closed]

I found this in a stream in Medicine Bow-Routt National Forest, Wyoming. One side (2/3 length) has a pointy pyramid with four faces; other side (1/3 length) has four faces but with with an edge ...
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How do people determine initial ratio of the parent nuclide and daughter product in radiometric dating?

I understand that we have zircon crystals that prevent entering or leaving of nuclide or lead after forming. But how cand we understand what was the initial ratio?
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Geological Differentiation: variables and size requirement

Geological/Planetary differentiation is one of those topics that gets glossed over in intro Geo courses. We know that differentiation occurs over deep time (and will never end) and is a result of the ...
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1answer
167 views

What is this yellow stone

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 ...
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What is the toughest rock?

I wonder which rock is most resistant to being cracked apart by a hammer, in other words, what is the toughest rock? What rock is most difficult to mine through? Hardness is different than toughness, ...
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1answer
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Mineral identification - please help!

I'm currently writing an essay on a mosaic in the British Museum, and am unsure about which stone the frame is constructed from (pictured). I would be most grateful for help identifying it. Thanks! ...
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1answer
52 views

Sink holes in drainage area

I live in Florida (aka the land of sink holes). Due to the flat nature of my area, it is common place for housing developments (and any developments really) to dig large drainage areas to give water ...
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1answer
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Is this a gold ore? I found it in a California creek next to a mountainside

I found this rock while hiking in a creek. It has some bits of white quartz, sheen and some brownish coloring. Does anyone know what it could be? Is there any possibility that it might be gold ore? ...
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What is this translucent and blue vein crystal, 7.5 < Mohs < 9, Lustre: Aventurescence

It looks like quartz, but it has blue veins on the surface that look died. Not all surface scratches are blue though. Hardness: > 6.5. Nail file will not scratch it. > 7 quartz will not scratch it. >...
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1answer
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What is this translucent blue-green oblong crystal?

I think it might be aventurine of some sort, but I'm not sure. Hardness: It is harder than a steel nail file. The file leaves a track, but it rubs off, leaving no mark. I scraped it on the bottom ...
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1answer
49 views

How do we detect floods?

How do we know that there was a flood at a certain place at a certain time. For example if there was a flood in place A 200 years ago. How could we detect it?
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1answer
53 views

What type of rock is this? Help [closed]

Please help me identify this rock. I’ve found it in a cave.
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1answer
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What minerals are in this rock? [closed]

Can anyone venture a guess as to what minerals are in this rock? I’ve had it for years and have never been able to identify it. I believe I got it somewhere in Northern California but it was from a ...
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Is this Black Serpentine?

I found this rock at a lake edge in Co. Sligo Ireland,its shiny black,leaves a black streak, weighs 320 grams displaces 125ml of water which gives it a density of 2.56 https://www.youtube.com/watch?v=...
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The differences on the atmospheric transportation for various trace metal in atmosphere

I have known that the atmospheric lifetimes of chemical species were highly dependent on their physicochemical properties. For example, $SO_2$ might exist for 5-8 days, while $NO_2$ could only exist ...
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1answer
123 views

What type of rock is this, Nephrite?

Its a very dark green opaque smooth rock, resists stainless knife blade 6.5-7 hardness, its 4x2cm, aprox 40 grams weight. I found this rock among cobble stones in County Roscommon Ireland.Its not ...
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3answers
156 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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1answer
87 views

What type of ore is this?

I have found this metal somewhere in a semi-desert area in Ethiopia. The place has no mountains and has no human contact yet. It is magnetic and has some rust on the top which can be removed using ...
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0answers
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why igneous phosphate rocks contain less uranium than sedimentary rocks?

Sedimentary rock phosphates contain much higher concentrations of potentially hazardous elements (As, Cd, Cr,Pb, Se and U)than igneous rock phosphates. Why? Is it because U concentration in magmatic ...
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3answers
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Need help identifying rock formation

so this is my first time here because I need help in identifying the features on this rock formation. https://www.flickr.com/gp/158064920@N05/6USrY9 Thank you in advance.
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When will the weight of melted polar ice release the (currently stuck) subduction of the oceanic plate West of the Oregon coast?

Melted polar ice water makes the oceans deeper on average. The extra water on top of the oceanic plates makes them sink relative to the continental plates. This relative vertical displacement will ...
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Why are there no deep caves in the continental US?

According to http://www.caverbob.com/wdeep.htm and http://www.caverbob.com/usadeep.htm, the only cave over 1000m deep in the US is a lava cave in Hawaii. In the continental US the deepest is 505m. On ...
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1answer
61 views

Rock type identification

Found this rock in western Ireland among many other like this one, its scratch resistant to a stainless steel blade, its blackish with light green spots and some tiny Pyrite crystal inclusions, it ...
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Formation of Hematite on Mars via Perchlorates as an Oxidizer

Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity. A comment to the answer to the question: How do hematite and magnetite form? states that ...
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1answer
57 views

Brown rock with hollow black interior?

We found a brown hollow rock in the woods in Sabine Parish, Louisiana , US. The tip of the rock had broken off, exposing the inside which is a black shiny rock. Someone told us that it may be a ...
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1answer
37 views

Do there exist reasonable numbers on the density/radius/mass of the various geological layers of the Earth?

I've been doing some math on the radius of the core (inner core in particular), and I keep getting what look like nonsense results. The composition is supposedly nearly all iron, close enough to it ...
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1answer
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Carbonaceous Chondrite [closed]

Can you please help me identify this rock? Is it a meteorite; if so, what kind? I sought the advice of the only scientist I know, but geology is not his primary field. He suggested a mineralogist ...
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1answer
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What is diffuse plate rifting?

For example in the Philippine Sea Plate the West Marianas Ridge has formed due to diffuse rifting in the south of the Marianas trough. What does it mean?
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1answer
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Identification: mystery rock with golden features and shimmer

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 ...
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1answer
71 views

What is this rock. Solid, Heavy, Metallic. Unknown origin

A few weeks ago i found this rock in the geology collection cupboard that my Geography teacher inherited from his predecessor. It is numbered 3729 but no list exists of the collection so we can not ...
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Which is naturally more radioactive: a tertiary or cretaceous sandstone? Why?

I've come across this question in a Petrophysics exercise regarding the Gamma Ray well logging. And I don't know how to solve it. This is the "believed" AFAIK session Natural radioactivity on a ...
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1answer
139 views

Identify yellow-tinted translucent mineral

I found a mineral near the hexagonal rock formations in High Island, Hong Kong that I'd like to get ID'd. It has a greasy and subadamantine lustre. It can scratch a U.S. Quarter Dollar and some types ...
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1answer
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would someone be so kind as to identify this rock i found? [closed]

What is this rock I found, it's got little glittering things on it. I found this in Sussex county New Jersey, it was used to line my driveway with a bunch of other rocks, other than that I don't know ...
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Is it ever possible for an continental plate to subduct under an oceanic plate?

It is well known that oceanic plates subduct under continental plates. This may be attributed to the plate's age and density, plus the water on top of it. So I was wondering if it is ever possible for ...
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how best to preserve the color of my amethyst geode?

Will bright indirect light cause an amethyst crystal to fade? How about an overhead LED light? How is best to preserve the color of my amethyst geode? Thank you!