19 votes
Accepted

Can ultrasounds be used to map the density of large underground regions?

Sound-like waves are routinely used to image the subsurface, but mostly well below the ultra-sound band. Several methods involve sound-like vibrations: Reflection seismic — the most important ...
Matt Hall's user avatar
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19 votes
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Why would India have so much thorium on its beaches?

why would India have so much thorium on it's beaches...? Because monazite. Monazite is a rare earth element phosphate, with the formula CePO4 (where Ce stands not only for cerium, but all of the are ...
Gimelist's user avatar
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10 votes

Are there minerals which are not been found on earth but which are still possible to exist?

To answer the first part, there are many minerals on earth which do not involve silicate bonded structures. For instance, non-silicates (minerals of carbonates, sulfides, sulfates, phosphates, and ...
Tachylite's user avatar
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9 votes

Connection between microbes and serpentinite?

The most common explanation for microbial activity in serpentinites is the exploitation of abiogentic hydrogen and methane formed during the serpentinisation process. Quoting the abstract of a recent ...
Gimelist's user avatar
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9 votes

What is the geologic origin of Cryolite, and could there be more?

Ivigtut Cryolite deposit, Ivittuut (Ivigtut), Arsuk Fjord, Sermersooq, Greenland deposit is the first and largest occurrence of Cryolite but it is not the only location to report Cryolite. Some of ...
Earth Science Expatriate's user avatar
9 votes

Are there any areas on Earth with purplish-colored soil/sand/rock/land?

Soil color is highly dependant on the oxides and other minerals in the composition. Purplish tones appear to be possible by inclusion of manganese oxide compounds. There are locations in China that ...
Zintlions's user avatar
9 votes

Are there probably decent oil fields located in the middle of the ocean?

Are there probably decent oil fields located in the middle of the ocean? tl;dr: no. Hydrocarbon deposits form by thermal maturation (i.e. slow and mild heating) of buried organic matter (i.e. dead ...
Gimelist's user avatar
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9 votes
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What are the cubic formations found inside Larimar gemstones?

Calcite and hematite may not be the the answer to my question Hematite is not the answer, but calcite is. The inclusions are not cubic, they are rhombohedral. This is precisely how calcite looks ...
Gimelist's user avatar
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8 votes
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Where can fluorite be found on Long Island, New York?

I do not know of fluorite being reported to occur on Long Island. If fluorite is found in NYC, the Natural History museum might have specimens. You might try contacting a mineralogy / mineral ...
Earth Science Expatriate's user avatar
8 votes

Which Earth minerals would Moon colonists miss the most?

The composition of Moon rocks is pretty much the same as that of Earth. However, none of the processes that concentrate specific minerals in one location (i.e. into a mineral deposit useful for mining)...
Camilo Rada's user avatar
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7 votes
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How do hematite and magnetite form?

In nature, iron can be either metallic ($\ce{Fe^0}$), ferrous ($\ce{Fe^2+}$) or ferric ($\ce{Fe^3+}$). In hematite, all of the iron is ferric: $\ce{Fe^3+_2O3}$. In magnetite, it is a combination of ...
Gimelist's user avatar
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7 votes
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What is the geologic origin of the Bauxite deposit in Bauxite, Arkansas, and could there be more?

The short answer is, bauxite requires a particular alumina-rich source rock and a specific set of conditions and processes to concentrate the aluminum in a specific order. From the Encyclopedia of ...
Spencer's user avatar
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7 votes
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What is serpentinization, in the context of disappearance of surface water on Mars?

does serpentinization just refer to the formation of some hydrated minerals that happen to be of a class that is historically been referred to as serpentinite or it's subgroup Yes. In simple terms, ...
Gimelist's user avatar
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7 votes

What kind of purple stone is this?

That's amethyst, a violet version of quartz See here
JulPal's user avatar
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7 votes

How can the 'crystal cleavage' of apatite have a four-digit number?

This is not a four- digit number but four separare numbers called Bravais-Miller indices. Bravais-Miller indices descrive the orientation of a crystal plane relative to the symmetry axes of a crystal,...
Oscar Lanzi's user avatar
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7 votes
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Why is silver found mainly in lead

This may not be a complete answer, but a big misconception here may be that silver is found "in" lead. It would be more correct to say that silver is more concentrated in the lead ore ...
desander's user avatar
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6 votes

Muscovite with pleochroic halos?

It's biotite. Not muscovite. That's why you have the pleochroic halos in it. I don't understand why you are saying that the interference colours are like muscovite. First of all, the lack of cleavage ...
Gimelist's user avatar
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6 votes

What is the white coating "patina" we often see on deposited chalcedony/agate?

The white "patina" is most likely some form of opal as you suggest. I did some research and I'll explain how the agate becomes opal and why it's more common in the eroded rock. Some ...
Brittan Wogsland's user avatar
6 votes

Are there any areas on Earth with purplish-colored soil/sand/rock/land?

Yes, there are. Here are some examples from Southern Israel: Another exceptional example is the "rainbow mountain" in Peru: The cause of these colours is the usually trace oxide amount in the soil. ...
Gimelist's user avatar
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6 votes

Which Earth minerals would Moon colonists miss the most?

It is unlikely anything other than salt would be derived from sea water. The largest deposit of gold is dissolved within the worlds oceans - in terms of tonnes of metal. The problem with extracting ...
Fred's user avatar
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6 votes
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Melting point of minerals

Start with my answer to this very highly related question here: https://earthscience.stackexchange.com/a/2742/725 The melting point of minerals in isolation, or a pure substance is higher than ...
Gimelist's user avatar
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6 votes
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If the study of "minerals" is covered by inorganic chemistry

The study of minerals is the field "mineralogy" In some ways it would be a subset of inorganic chemistry, restricted to crystaline materials of natural origin. However, mineralogy includes the ...
haresfur's user avatar
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6 votes

How are minerals classified?

Minerals are defined by chemical composition and crystallography. Dana classification scheme or new Dana classification scheme divides known mineral species in eight broad groups based on primary ...
Earth Science Expatriate's user avatar
6 votes

Why is the Lunar crust anorthite?

A base-level justification is that calcium is much more abundant than sodium or potassium - about 10 times in bulk earth, and double in the crust. Since the moon is thought to have formed as a result ...
desander's user avatar
  • 415
5 votes

Is porphyritic texture always indicative of a 2 stage cooling process?

Is porphyritic texture always indicative of a 2 stage cooling process? Not necessarily. While it is a nice simplification for undergrad textbooks and it nicely explains phenocrysts in some simple ...
Gimelist's user avatar
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5 votes

Why does halite have perfect cleavage at the (110) plane?

I think the commenters have identified the issue. Halite does not have perfect cleavage along the {110} plane. As recorded in Mindat, Halite has perfect cleavage alone {100}, {010}, and {001}. This ...
Microscone's user avatar
5 votes

Why are there craters on the moon?

I'd like to expand on jamesqf's answer. But first, lit side of the moon and the dark There are no "lit" and "dark" sides of the moon. It rotates, and whatever is dark now will be lit in two weeks ...
Gimelist's user avatar
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5 votes
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A sedimentary rock with only minerals

This is a really bad question, because all three can lack fossils, or all three can have fossils. The definition of "minerals" is also a bit unclear, because fossils are also made out of minerals. I'...
Gimelist's user avatar
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