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Questions tagged [rocks]

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

155 questions
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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 showing they are considered not metamorphic rocks…
Treblig
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5
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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 white clay like substance like melted marshmallows. I…
Fifi
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Why does fracturing occur along a specific plane or region of the rock?

In this typical image of rock fracturing, why do the joints / fissures occur where they do, as opposed to, say, along the line drawn in blue on the image? More specifically, what characteristics of the rock grains on the separated joint surfaces…
charlie_sar
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What would create the triangles in this rock I found in the Lehigh River

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 Rock.
Natalie
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How accurate are float samples when looking for outcrops?

Near an old fire-trail I found a single fist-size igneous rock that I identified (as an amateur geologist) as belonging to a formation that is not known of in the area but is known to occur in the neighbouring district, although not common there.…
Tom P
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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.
Tulip
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1
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1 answer

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 relation that includes Cp but the rock type is not…
Charitoo
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I found this rock on Laguna Beach

Rock found on Laguna Beach. It is not sand stone and is heavy for its size 3" x 2". It is rather dense. Click the image for full size:
Herb
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classification of oil shale

Could we classify oil shale as a biochemical sedimentary rock ? Oil shale is a muddy rock contains Kerogen. So I think in oil shale to be a mixture of Kerogen and mud sediments, and that's not the case, for instance, with the biochemical limestone…
Asmaa
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0
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Rock identification ? What kind of it is?

My co-worker had this rock and told me found just behind the store, Big R, and put on the table in the office. Location is Trindad, Colorado.
PROBERT
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What is the definition of "ground-up shell"?

The archeologists use the term "ground-up shell" to designate a type of temper used for pottery. What is this material? Earth containing fossilized mollusk shells? I noticed the term is also used in texts about oysters.
Fructibus
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Color in Gems and Rocks

Why is it that gems/ rocks, such as Ruby, Sapphire, Topaz, etc... all have their own unique colors? Is this something that happens from chemical attraction with each stone upon formation?
Mark
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