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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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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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295 views

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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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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173 views

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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347 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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113 views

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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69 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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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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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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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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61 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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48 views

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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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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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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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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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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2answers
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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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64 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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84 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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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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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
136 views

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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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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81 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
151 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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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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215 views

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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53 views

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!
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Where to start searching to find more radioactive minerals?

I'm pretty new to all this... I've recently purchased a Geiger counter, and am hoping to locate rocks like pitchblende and other radioactive minerals for my collection. I'm based in the North West ...
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82 views

Please explain how this rock could be shaped like this [closed]

i found this amongst some river rock. Please explain why or what happened to it.
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135 views

Is this Jadeite Jade?

Bought this online, shipped from India, I was told that it is Jadeite Jade and not Aventurine, it comes from China and India, I tumbled one piece. The piece on the left is 2 3/4 inches. A beautiful ...
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94 views

Using acoustics to measure the composition, density, and hardness of layers

I am an engineering student at Alfred University and some fellow classmates and I are doing a competition, but one of the tasks we need to complete is autonomously measuring the composition, density, ...
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59 views

Asking about type Fossil [closed]

Can any one help me to identify this type of fossil ? Its dolomite limestone
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Identification of a rock. White marble? [closed]

Could you please help me identify the rock found commonly near many of the ancient Greek foundations and rubbles? This one was at the base of Poseidon's temple. White in colour with a smooth texture ...
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1answer
94 views

What are these Pebbles

Found these Pebbles at a lake edge where a Serpentinite belt runs through, there are lots of serpentine pebbles along this lake in Co. Sligo Ireland. The larger pebble is 1 5/8'' a Yellowish white ...
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2answers
245 views

I found this strange spherical stone in Gillette Wyoming. I have no idea what it is. Please help.

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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63 views

What kind of purple stone is this?

I found this stone and I do not know what type of stone is this?
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2answers
136 views

Is this Mutton Fat Jade?

Found this near the Shannon River close to Carrick on Shannon Irelandenter image description here Could this be Mutton Fat Nephrite Jade? Thank you
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1answer
48 views

What is this rock found in the Illinois Valley of Southern Oregon?

I found this odd shaped rock along a rocky river bed (dry) near the Illinois river in Cave Junction, Oregon. It is shaped like a Club and is super heavy. It has a distinguishable ring around the ...
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1answer
71 views

Please identify- no origin known but given to me by a geologist

A very dear man who love his job as a geologist gave this to me. He’s been all over the country so I have no idea where he may have picked it up
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Please help identify

I have had this rock in my yard for close to 10 years. It was left behind by the previous tenant. Can you help identify it? It has layers, a mixture of soft and hard, and is tan to white in color. ...
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heavy, brown, rock with crystals, please help identify

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 ...