Questions tagged [mineralogy]

questions relating to the scientific study and identification of minerals.

17 questions with no upvoted or accepted answers
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Chloride and evaporation

I have a layered aquifer with water that contains high concentrations of calcium and sulfate (~400 mg/L Ca2+, ~1300 mg/L SO42-), at 50 cm below ground surface (bgs), 250 cm bgs and 300 cm bgs. The ...
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1answer
169 views

Why would CaO be more finely spread than K2O in Granodiorite?

I recently interpreted some XRF data on samples of a granodiorite which were classified under three different types of physical characteristics: very little, mild and significant levels of weathering. ...
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558 views

Could this be pyroxene twinning ? (thin section)

I found this beautiful euhedral pyroxene crystal in thin section today. There is one thing that I can´t explain though. In crossed polarizers, the crystal shows two different interference colors, ...
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0answers
392 views

I have found this structure in thin section. What is it?

I have been observing a nepheline specimen under polarized light and found some interesting places. I have taken several images. The first shows a micro-geode with parallel polarizers, second with ...
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0answers
28 views

Can humidity changes induce stacking-sequence changes?

My understanding is that some minerals with layered crystal structures will reversibly absorb water with changes in humidity. Are there any minerals where this reversible absorption leads to a ...
2
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1answer
37 views

“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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127 views

Green Rock Identification

This rock was found in the highlands of Scotland in the mountains.It is 2 1/2''x2 1/8''x 1'' it has a density of 2.95 leaves a clear streak weighs 130 grams and a hardness of 6 on Moh's scale.This ...
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33 views

Formation of dolomite

What are the kinetic barriers to dolomite precipitation? Does it precipitate out in solution as quickly as Calcite does?
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38 views

A chemical formation or constructed by microorganisms?

This mineral formation was at the side of a fresh water canal in Gürpınar, Van, Turkey. It was dug out from the bottom of the canal. It is very brittle. I know that the natural water sources in the ...
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57 views

Can you help me identify my rock?

I found this rock in my yard. Can someone please identify it for me? I’m not sure if you can see the blue hue on the rock in the picture! (https://i.stack.imgur.com/cuklH.jpg)
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26 views

Detecting the hydrothermal alteration zones?

Is it possible to use remote sensing to determine Hydrothermal alteration zones without resorting to collecting samples from the Area of study?
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85 views

Formation of minerals from decomposition of soil

I was wondering if aerobic decomposition of organic rich soils, also rich in calcium and sulfur, can result in the precipitation of gypsum. My thinking is the decomposition would release the ...
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216 views

What is solidus and liquidus temperature of granite?

My understanding is that because a rock is composed of variety of minerals, so it does not have fix melting point, rather there is a range below which whole rock is solid and above which whole rock is ...
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85 views

Is it ok to use biology microscope for gemological purpose?

Is it ok to use biology microscope for gemological purpose? What's the difference?
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22 views

Space Symmetry Groups: Wyckoff notation, diagram and positions

In the subject: "Introduction to Chemical Geology", I have given the spatial symmetry groups. At present, I know the different symmetry operators: rotation axes, center of symmetry (or inversion), ...
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3answers
80 views

What kind of red rock is this?

I don’t know much about were I live, I am from ny and only moved here a few years ago. I found it in Smithfield nc we’re I love with my dad and kids now.. I wish I had more information. Yes the rock ...
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18 views

How does chalcedony containing quarts and mogánite form?

I just learned that the cryptocrystalline form of silica, chalcedony, usually contains 1-20% of the monoclinic $\ce{SiO_2}$ mineral mogánite as well as the much more common hexagonal quartz. With time ...