Questions tagged [rocks]

Questions about rock types, formation, chemistry, and physics. If you just want help identifying a rock please use the tag "identification-request".

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Help me ID this item found in a car park

I found what I thought was a granite chip.It is in fact metallic, it is magnetic with a density of 7.3 g/cm . It looks natural. Interestingly 2 surfaces are flat and with extrapolation form an exact ...
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Identify my rock

I got this rock years ago in California. I have always wondered what it is. Please help me identify it! Thanks!!
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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 ...
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What kind of rock this my son find in the Colorado river? [closed]

1: https://i.stack.imgur.com/HmpL4.jpgstrong text my son found this rock in laughlin nv in the colorado river, it weighs around 2 lbs
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Can anyone identify this, found in Montana .Found 30 miles from Beartooth mountains. Found many vary in size and color, from clear to brown & redish! [closed]

Translucent layered rock, more light hits the more color seen, lightweight for mist part. Have single layer to multiple layered, clear to brown to reddish.
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Basalt, slag or meteorite? [closed]

I found this rock on the edges of a known Drumlin in North East England. It looks to be a fragment from a larger piece. It attracts a magnet strongly, it weighs 150 grams. It has vesicular holes (on ...
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How was this egg shaped rock made and what is it? [closed]

The following small egg-like rock was found laying on the ground in Tampere, a city in southern Finland. It weights about 950 grams, has a volume of about 360 cm3 and thus a density of about 2600 kg/...
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Rock ID: black rock found in Central Europe [closed]

I'm note sure if it's an anthracite, augite, jet (lignite) or something completely different. I don't know where exactly i found it because it's from my old rock collection. I would appreciate your ...
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Rock ID: smooth, black, durable rock from Lake Ontario

What is this black rock? I found it beneath the waters of Lake Ontario near the shoreline, it is a dark greyish-black with small flecks of mineral deposits on it that are visible in the light. The ...
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Help! Can anyone identify this deep blue rock, quartz, crystal thing from Washington?

I was like 10 waiting for my dad to get off work. He was a surveyor and brought this blue rock thing with him for me when he got off. He said they were surveying and his friend took a pickax to a rock ...
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1answer
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What kind of rock is this? (Sedimentary) [closed]

This rock was obtained from a nearby quarrying from our grandparents' house on an island. It has a couple of bronze/mud colored linings on it and a bunch of scattered white areas. Could also see tiny ...
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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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Identification required, rock formation found whilst on holiday in Cephalonia, Greece white object embedded inside?

This rock was found in kephalonia Greece, on a beach in lassi. The rock is black in colour, smooth with thumb like prints, very metallic smell and very slightly magnetic. We took this rock to oxford ...
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Can anyone help me identify this rock found in Tulsa Oklahoma?

I was working in my front yard in Tulsa Oklahoma and ran over this rock with my lawnmower. It was logged in the ground enough I didn’t see it. It’s 2.5 inches in length. Black in color with what ...
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What kind of red rock is this?

I don’t know much about were I live, I am from ny and only moved here a few years ago. I found it in Smithfield nc we’re I love with my dad and kids now.. I wish I had more information. Yes the rock ...
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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 ...
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Please identify this rock

I found this rock along the Illinois river basin in cave junction, oregon. It was laying on the top layer of a massive beach of rock. It's shape is what drew me too it, then after closer inspection ...
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Can someone please help identify my rock

Can somebody please help. I found this rock on the beach in the south of England. It seems to have a number of small shards of what look like crystal or glass spread around it whilst the rock itself ...
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1answer
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Help to Identify a Rock Found in Gray Clay [closed]

Found digging a pond. The rock was inside Gray Clay 18 feet below grade. The person who gave it to me tried cutting it with a grinder. This left an area that looks like steel. Location: ...
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I found this stone with metal linings can someone identify it?

I am more curious about the metal on the surface (if it's even metal?) on this stone :) I don't really remember where I found it, probably at this beach of the Baltic Sea, but there is also a chance ...
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4answers
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What is this Lake Michigan rock?

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 ...
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1answer
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What types of rocks are these [closed]

I can’t figure out what type of rocks these are I would like to create pigment out of them to make a watercolor want to make sure they are safe, one is brick red the other is more of a deep magenta, ...
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1answer
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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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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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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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Why is coal classified as a sedimentary rock?

Something just clicked in my head today. Rocks, by the definition I was taught, are composed of minerals which in turn are by definition not organic, so they are or were not alive. However. Coal, ...
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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.
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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 ...
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Pinkish rock with red 'veins'

I found this rock in Smithfield NC. It does scratch glass. A butter knife didn’t scratch it. When you hold it to a light it has an orange glow. It didn’t leave anything on porcelain.
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What type of rock is this [closed]

![I found the the rocks is Eastern Arizona by the Black Mesas. They are white with a few orange patches. The inside kind of looks like quarts.
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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 ...
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540 views

What is this white rock with black speckles throughout?

I was wondering if you have any ideas on what kind of rock this might be? I know that it doesn't effervesce with HCl (no reaction with hydrochloric acid at all) and the size and shape of each grain is ...
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Help me identify my rock is it jade?

Found this rock it looks like a vein of Jade but I have no idea. This is the inside of the rock. I found it already broke the rock is wet in the pic. It's is a hard rough texture and the green in the ...
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1answer
264 views

Rock identification: gray with small dark lines/inclusions all over [closed]

Gray stones with short small dark shiny lines all over it. Found it on the beaches of Newport Rhode Island.
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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 ...
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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
847 views

If rocks are stones, what type of rock are gallstones? [closed]

From Wikipedia: Rock or stone is a natural substance, a solid aggregate of one or more minerals or mineraloids. For example, granite, a common rock, is a combination of the minerals quartz, ...
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284 views

Is this rock Massive Epidote?

enter image description here This is a close up of outside of chipped off piece, and inside alsoI found this rock in Co. Donegal Ireland on a river bank buired under the dirt. It weighs 16.4lbs- 7....
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1answer
294 views

Can someone please help me identify my rock?

Hey guys! My name is Brent and I found this rock over 20 years ago while swimming with my siblings in Lake Huron near Kincardine, Ontario. I actually found it under water at one of our favourite ...
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Is this Mutton Fat Jade? [closed]

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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Can someone help ID this rock [closed]

Found today in a creek in Indiana, has a geode look and the broken edge shows red opaque facades.
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Is it an egg? What type of rock please? [closed]

This stone was found by my uncle in Western Queensland. It’s light brown in colour and smooth. It's very heavy for its size. 780 grams. Pocket knife doesn’t scratch it. many thanks.
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what type of rock is this? blue/green and brown [closed]

I found this rock while up in the mountains and I have no idea what type of rock it is.
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1answer
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What is this figurine made of: [closed]

Have several of these animal figurines, MADE IN USSR on bottom. Can't figure out what type of rock it is made from. Any ideas?
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Rock identification: meteorite or lava?

I was told by a crystal quartz store owner it was a type of lava rock but I have high doubts. hardness: diamond size: 4'' $\times$ 4'' weight: 1.5 lb location: unknown smell: sulfur trait: ...
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1answer
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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. ...
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Are the processes of the rock cycle currently in dynamic equilibrium?

The standard representation of the rock cycle usually looks like this: Does each stage of the rock cycle currently balance? That is, are the various processes in dynamic equilibrium, so that the ...
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496 views

Identification of a rock from Kentucky [closed]

I was hiking the other day in southeastern Kentucky and ran across this rock on a river bank. I've never seen a rock like this before. Can anyone here identify it?
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598 views

What kind of rock is this?

We found this today in Acton CA USA. Would like to know what it is.