Questions tagged [rocks]
Questions about rock types, formation, chemistry, and physics.
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What is the difference between basalts and andesites!
I understand that basalt is darker in color and has less silica but do not understand how these reflect the underlying minerals/mineraloids (if mineraloids are even present in these rocks)???
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How do these holes form?
I was casually browsing the google earth street view map today. And I noticed strange cavities in a rock wall on Henderson Island, a coral island in the South Pacific. What could have caused this to ...
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Subantarctic islands: man-made rock cairn or natural formation?
When surveying penguin colonies on subantarctic Antipodes Island, we found a cave that features a strange rock formation:
The formation does not appear to be particularly exposed to the elements so ...
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Are there enough rocks that are useful to burn that Paleolithic people would have experimented with them?
I'm not sure where to ask this question, but I thought there might be people on this list who are familiar with rocks and minerals. I've been thinking about the first smelting of ore (which seems to ...
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How to extend the Wyllie time average equation to multiple constituents
I understand the Wyllie time average equation
How to extend it to multiple constituents ?
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Are These Leaf Fossils Found Near a Texas Lake Shore?
I recently came across some intriguing specimens near a lake shore in Texas and am seeking your expertise to help identify them. The objects have a few characteristics that lead me to believe they ...
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Why is basalt denser than granite?
If lava is nothing but magma breaking through the earth's surface, then why is basalt more dense than granite?
I understand that something happens during the cooling process, but cannot find any ...
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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 ...
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Mud cracks formation
Are mud cracks formed during rock formation or after the rock is completely formed?
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Identifying dense magnetic rock with tubular features [closed]
I recently found a few rocks scattered in a valley, without any clues about where they may have come from (they did not look anything like the local soil, rocks, or layers of rock that could be seen ...
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Is there a theoretical maximum size limit for a rock?
There are many types of rocks: igneous rocks, sedimentary rocks, and metamorphic rocks. Some rocks are simply huge. Some of them are tiny. Is there a theoretical upper limit on the size of a rock, and ...
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Why does calcium occur together with felsic rocks and magnesium with mafic rocks if calcium is denser than magnesium?
Felsic rocks contain a lot of sodium, potassium and calcium (and a great deal of aluminum), while mafic rocks consist of a lot of magnesium with iron....
Why is this?
Why is magnesium (z=12) in the ...
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Identify source of rings pattern in flint
This stone was found at the beach on the Danish side of Øresund (Amager strand in Copenhagen). I believe it is flint, though I am not sure. There is a pattern of rings on one of its sides (see photos)....
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Hexagonal phenocrysts with a metallic luster?
I recently realized that I am surrounded by interesting rocks. Having no background in geology nor geologist friends, I rely on online resources to navigate the intriguing stuff I stumble across. But ...
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Are rocks extracted from deep drilling, brittle due to pore pressure?
When a saturated rock sample is rapidly extracted from a place with high water pressure, as happens in oil drilling or deep mining, the water is trapped inside the rock at high pressure, trying to ...
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