Questions tagged [mineralogy]

Questions relating to the scientific study and identification of minerals.

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Difference between crystal and mineral

What is the exact difference between a crystal and a mineral?
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What is the "healthiest" rock?

When talking about rocks, i.e. an aggregate of minerals, which type would be the "healthiest" I'm not talking about some voodoo crystal-healing stuff here, just if there is any rock ...
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Looking for Rock/Mineral Identification Flowchart

As a christmas present, I bought a box of minerals/rocks for my girlfriend, who recently got interested in geology. Unfortunately, she could not attend the identification class in university. The box ...
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3 votes
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What are the compressive strengths of goethite and magnetite?

I am attempting to determine what the compressive strengths are of the minerals goethite and magnetite. None of the research I did has proven to be fruitful. What I have found: multiple studies ...
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4 votes
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Is there any mineral that survives hard degree metamorphism?

When a protolith enters in metamorphism, the minerals transform in other new stable minerals while the pressure and/or temperature increase. Is there any mineral that would not be affected by a high ...
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How to genetically classify a weathering mineral or a mineral formed in soil?

Coming from this question and the answer, a proposed genetic classification of minerals: Endogenic: Magmatic, Metamorphic, Hydrothermal. Exogenic: Supergene, Sedimentary. My question is how would ...
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What questions to ask to students from a mineral guide dataset?

I am programming an app that consist in 180 mineral sheets of interest for geology students. My database have the following fileds: Identifier Name Name 2 Type Class Formula System Environment1 ...
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Why is Melanterite white or colorless?

I've read that melanterite (FeSO4*7H2O) is colorless or white and gets to be green to blue with increase in Cu2+ impurities. But from my chemistry experience I know that iron sulfate is green when in ...
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Can geochemical anomalies of stream sediment samples be used directly for mapping targets?

We know that geochemical dispersion in stream sediment is much widespread, facilitating discovering mineral targets in a regional scale. However, we also know that there should be discrepancy in space ...
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Isotopic dating of metamorphic rocks

I read in my physical geology textbook that sedimentary rocks cannot be dated using isotopic dating, because they are formed from fragments of other rocks and minerals, which if you were the subject ...
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Why were Fe-oxides not usually used for finding skarn Fe ore deposits in geochemical exploration?

I found that Fe-oxides were usually not used for vectoring Fe mineral deposits of skarn type in geochemical exploration. As an indicator element, the common practice told us Fe-oxides should be the ...
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Identifying metallic element or compound in murine clay

I have been doing a lot of digging in a thick murine clay as part of a construction project. In the course of doing this work, we noticed significant bands and streaks of blue color in the clay, which ...
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Artifical Ore Genesis?

From my understanding, the formation of ores can be reduced to a simple three-step process of the removal of minerals from a source via some mechanism, the transportation of these minerals, and ...
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Avoiding fake trinitite

I would like to get some trinitite for my rock and mineral collection. The problem is that there is apparently a lot of fake trinitite for sale in the internet. How do I avoid the fakes, and be sure I ...
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What kind of rock is this? [closed]

A few years ago in Venezuela, parque nacional de Cainama, the tourist guide found and gave me this rocks, he told us that a geologist told him that those could be radioactive but no one believed him. ...
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How to identify chemical property and structure of rocks?

I am interested in identifying the properties of rocks. For example, black opal is shiny and can emit 5 different colors based on different lighting conditions. Is there a way for an amateur to be ...
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Ore Deposit Identification

What type of ore deposit does this rock best represent? A rock with a porphyritic texture is cross cut by a stockwork of quartz veins. Bordering the veins is extensive alteration of the host rock. ...
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Feldspar content of coarse-grained igneous rocks

From the chart, I would say that plagioclase feldspar is more abundant in coarse-grained igneous rocks than alkali feldspar, as it is found in all three listed, whereas alkali feldspar is only present ...
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Quartz mineral category

Different learning resources categorise quartz differently. Strictly speaking, is quartz a silicate mineral or an oxide mineral?
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Cleavage of minerals

What is the difference between 3-dimensional cleavage and cubic cleavage? I think, they are the same, but I am not sure about if I was right or not.
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Hydrocarbon resources extension. How?

Pardon my naive question. But I heard this argument quite sometimes. One can find at the Schlumberger careers page the particularly interesting FAQ: “We are often told that oil is running out. Why ...
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How can the 'crystal cleavage' of apatite have a four-digit number?

On Wikipedia's page for apatite, the crystal cleavage is listed as [0001] or [0101], which I assume are Miller indices.... But how can there be four numbers/digits instead of two, like there usually ...
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1 vote
1 answer
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What causes dye to bleed from an agate stone?

I came across this review on Amazon. The cold drink was placed on top of the agate stone and the dye bled and left a permanent mark on the table. Why does this happen? Is it because of the ...
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Are there any sulphides, sulphates, carbonates that cannot be dissolved by aqua regia?

I was looking into these specific minerals: arsenopyrite, pyrite, chalcopyrite, barite, calcite, dolomite. I investigate issues with tellurides not showing expected gold concentrations. There is gold ...
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How does metamorphism change talc into soapstone?

My understanding is that soapstone is talc (hydrated magnesium silicate) which has been metamorphically transformed. However, it is not clear to me how this transformation affects the talc. What is ...
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7 votes
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Will the sea get saltier forever?

The sea wasn't always salty. It's been getting saltier over millions of years as minerals dissolve. Is there a natural limit to this process, or the will the sea keep getting saltier forever? Is there ...
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Why and how do quartz crystals change from cloudy/translucent to clear/transparent?

Two pieces of quartz people have given to me at different times have become gradually clear over the space of a few years. Previously they were very cloudy, translucent without any detail visible ...
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1 answer
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Does higher hardness means that A cannot scratch B regardless of any other variable?

You have object A of hardness 4 and glass B of hardness 6. Is this information alone enough to determine that, under any circumstances object A will never be able to scratch glass B? For a more ...
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What is the connection (if any) between jarosite and subsoil biological activity near Spain's Río Tinto?

In the short BBC video Spain's otherworldly red river, Ricardo Amils, a researcher in Spain's Astrobiology Center says the following (amateur transcription): Río Tinto is a peculiar place in our ...
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Introduction to Geology Books

I am a high school student who is thinking about going to university for Geological Sciences. I've had an interest in rocks and such since I was little, but I want to get an idea of what studying ...
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2 answers
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How to genetically classify a mineral resulted from weathering?

I am writing a mineral guide for smartphones which classifies minerals according to their formation environment. From sugestions on this related question, I changed the classification to: ...
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3 votes
1 answer
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What is the meaning of the subscript in the abbreviations of some minerals?

I have noticed that in many articles on minerals that I have read the abbreviation of some mineral has a numerical subscript, for example, occurs with the forsterite (Fo95-90, Fo92-84, Fo94, etc.). ...
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Is the association of fluorescent minerals calcite, fluorite, and apatite with fluorescent rare-Earth minerals a coincidence?

If I understand this answer and this comment correctly, minerals like calcite, fluorite, and apatite are "commonly associated with (Rare Earth Element) REE deposits", and like some REEs also fluoresce ...
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2 votes
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Ore Reserve Definition

I've seen many papers on mineral deposits say something along the line of "a 100,000 tonne deposit of Zn, 1% grade." Does this mean there is 1% of 100,000 tonnes which is 1000 tonnes pure zinc, or ...
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mineral prospecting in Iran

I live in Iran and I want to do personal mineral prospecting for natural crystals and gemstones and beautiful minerals. Unfortunately, there are no reliable information available. Anyone can help me ...
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Ore Deposit Determination

How are ore body sizes determined? What are the most reliable techniques of determining the size of ore deposits as well as their content?
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If the earth's core is made up of copper/other metals other than iron-nickel alloy, how our magnetosphere will be?

We know that our earth's core is made up of iron-nickel alloy and it is spinning to create magnetic flux all around our planet to create our life-saving Magnetosphere. And this also influences our 9.8 ...
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Can crystal lattices be analogue? [closed]

This question might turn out to be more about physics then geology so apologies in advance if that is the case. Years ago I read something that said in crystals "atoms have finite positions along the ...
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3 votes
1 answer
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Hyperspectral Detection of Ore

How can I use hyperspectral satellite imagery to remotely detect copper or any prespecified mineral deposit in general? Where can I find a database of the absorption and reflection bands of various ...
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5 votes
2 answers
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Is this classification of mineral formation environments correct?

I am writing an app for students that consist in 180 sheets of the most common minerals on Earth's Crust. One of the fields of the sheets is environment of formation. It is important to me to ...
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6 votes
1 answer
103 views

Does muscovite occur as a contact metamorphism mineral?

Does muscovite occur as a contact metamorphism mineral, with dacitic intrusion into dacitic rocks?
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"Obicular" structures in basalts

I found spherical or globular structures, structures in basalts of a greenstone belt which underwent alteration and deformation. However, in thin section, these structures have undeformed pyroxene and ...
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Database of color wavelengths of minerals

I was wondering about the physics of color, and now am interested in finding out if there are any resources (databases, text files, html tables, or pdf listings) of minerals and their associated ...
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2 answers
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What does the unit cell of petitjeanite look like?

The question in Chemistry SE What is the crystal structure of bismuth oxyhydroxyphosphate (BOHP)? is about a catalyst synthesized by accident. A link in this comment points to the page https://www....
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What's the difference between cleavage and fracture?

I see both terms refereing to fractures on crystals or minerals, so I wonder if they could be considered synonymous. If no, what's the difference between both terms?
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Can gemstones be cut into sheets? [closed]

TL;DR: Without lasers, electricity, or otherwise modern tools, could large transparent gems be sliced (like glass window)? So I’m world building. On this planet they have caves with enormous gemstone/...
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2 votes
1 answer
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Name of majorite endmember $\ce{Mg3(FeSi)Si3O12}$

Does the majorite garnet $\ce{Mg3(FeSi)Si3O12}$ have a name?
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1 answer
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An oblique-square-prism crystal?

Does any mineral crystallize in the shape of an oblique square prism? If so, what crystal system (monoclinic, cubic, hexagonal, etc.) would such a mineral fall under?
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2 answers
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How are minerals classified?

What exactly is done to classify minerals in Earth Sciences such as Geology? How can it be known if one mineral is the same as another if they should be visually different?
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6 votes
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Formation of Hematite on Mars via Perchlorates as an Oxidizer

Hematite on Mars is generally thought to have formed either in pools of water or from volcanic activity. A comment to the answer to the question: How do hematite and magnetite form? states that ...
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