15 votes
Accepted

Is it safe to keep volcanic sulfur at home?

Short answer: Assuming it is sulfur (likely, but I'm not addressing other compounds in this answer) you should be fine as long as you keep it away from heat (melts at a low temperature and is somewhat ...
GrapefruitIsAwesome's user avatar
11 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
  • 111
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
Accepted

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
  • 23.1k
8 votes
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Why is streak different from color?

It mostly has to do with the fact many minerals are partially translucent. Trace impurities or even crystal structure can dominate the color of a translucent material but when ground in to a fine ...
John's user avatar
  • 6,906
7 votes
Accepted

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
  • 3,548
7 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
  • 23.1k
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
  • 3,826
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
  • 23.1k
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
  • 23.1k
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

How is it possible for rocks to be trapped within another type of rock?

There are three major types of geological formations that contain or are composed of various rocks: breccia conglomerate xenoliths Breccia The word breccia comes from the Italian word for rubble. ...
Fred's user avatar
  • 24.7k
5 votes

Were all of Earth's minerals created before Earth's formation, during, or after?

This is a very interesting topic that in the past several years has reached the spotlight because of the work of Robert Hazen on the concept of "mineral evolution". Minerals are basically just ...
Gimelist's user avatar
  • 23.1k
5 votes
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Deadly minerals

I assume by "mineral excavation" you mean mineral collecting. I've collected minerals for years. In general the biggest danger is naivete not the minerals themselves. You need proper safety ...
MaxW's user avatar
  • 511
5 votes

What is meant by phase-change in mantle?

I'd like to add to Gordon's answer. A phase change in this context does not only refer to the change in the state of matter (e.g. liquid to solid) but a change in different solid states as well. ...
Gimelist's user avatar
  • 23.1k
5 votes

Have fossils ever been found in the asphalt lakes of Trinidad and Venezuela?

Trinidad Quote from https://www.smithsonianmag.com/travel/trinidad-and-tobago-nature-and-scientific-wonders-18329129/ Quite an oddity sits in La Brea in South Trinidad—the world's largest asphalt ...
samcarter_is_at_topanswers.xyz's user avatar
5 votes

What are the compressive strengths of goethite and magnetite?

I managed to find EFFECT OF MINERALOGY AND TEXTURE ON THE STRENGTH OF IRON ORE, which states the uniaxial compressive strength of goethite is 157 kg.f/cm2, which converts to 15.397 MPa. STRENGTH OF ...
Fred's user avatar
  • 24.7k
5 votes
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Is there any iron ore in New Guinea?

The island of New Guinea is effectively divided into two entities, the country of Papua New Guinea occupies the eastern half and the Indonesian province of West New Guinea occupies the western half. ...
Fred's user avatar
  • 24.7k
4 votes

Dissolved minerals

There are several processes that can cause a mineral to precipitate from solution. You mention one which is adding elements to the solution This could occur in a number of ways. For example, aragonite ...
haresfur's user avatar
  • 4,439
4 votes
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How does quartz form in calcite veins?

Your question is How does quartz form in calcite veins? But maybe a more appropriate question will be How does quartz not form in calcite veins? Quartz is one of the most common vein material ...
Gimelist's user avatar
  • 23.1k
4 votes
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The rock that gives birth to quartz sand

In only one minute of presentation there isn't time for detailed discussion, so one has to make broad generalizations which, on closer inspection, aren't quite true. It is true that most sand is made ...
Gordon Stanger's user avatar
4 votes

Is there any mineral identification techniques that works for all minerals?

Yes, it is called X-ray diffraction (XRD). It is done by machines that look like this: I'm not sure this is in the scope of your electronic engineering project.
Gimelist's user avatar
  • 23.1k
4 votes

What is meant by phase-change in mantle?

'Phase change' doesn't just mean liquid-gas-solid changes. It also includes mineral lattice restructuring in response to differing pressure-temperature conditions. There are also other solid-solid ...
Gordon Stanger's user avatar
4 votes

Why do gold deposits form only in certain areas of the earth?

I do agree with Gimelist how gold is accumulated through hydrothermal fluids, adding that the main driver is for this process is volcanism. There is, however, something interesting to be noted. We ...
Erik Bloem's user avatar
4 votes

Why does Australia have no chrome?

There has only been one chromium mine in Australia - the Coobina mine, in the Pilbara region of Western Australia. It is located 80 km south east Newman (23 deg 29' 31" south, 120 deg 16' 32" east). ...
Fred's user avatar
  • 24.7k
4 votes

Difference between pyrite oxidation and dissolution

Oxidation and dissolution are not the same processes, but they are related when discussing the breakdown of pyrite in near surface environments. Dissolution is a process(*1) in which the chemical ...
Gimelist's user avatar
  • 23.1k
4 votes
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I found this strange spherical stone in Gillette Wyoming. I have no idea what it is. Please help.

This is a so called Moqui Marble. A spherical concretion formed by sand and iron based minerals like limonite. Further information can be found here
JulPal's user avatar
  • 734
4 votes
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Preservation of clay items

Its chemically stable oxide, thus non-combustible, does not rot, and fairly hard. Clay ceramics (just ceramic covers a huge swath of materials) are very non-reactive, and fairly hard, both are ...
John's user avatar
  • 6,906

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