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 ...
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 ...
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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 ...
- 91
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 ...
- 23k
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 ...
- 6,803
7
votes
Accepted
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 ...
- 23k
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 ...
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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,...
- 3,556
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. ...
- 23k
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 ...
- 23k
6
votes
Plotting a mineral stability diagram
Remember that you are concerned about stability fields. The lines on your stability diagram are the places where two minerals are in equilibrium. One one side one mineral will be more stable, on the ...
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6
votes
Accepted
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 ...
- 23k
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 ...
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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. ...
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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 ...
- 23k
5
votes
Accepted
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 ...
- 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.
...
- 23k
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 ...
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 ...
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4
votes
Accepted
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 ...
- 23k
4
votes
Accepted
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 ...
- 14.2k
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 ...
- 14.2k
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.
- 23k
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 ...
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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 ...
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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 ...
- 23k
4
votes
Accepted
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
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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 ...
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4
votes
Accepted
What's the difference between cleavage and fracture?
They are not synonymous.
Cleavage means breaking along planes defined by crystallographic directions. For example, cubic crystals like halite, NaCl, often cleave along directions that follow the ...
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