Rocks and Minerals B/C

[Magikarpmaster629]

[b]Question[/b] (Click to Show Hidden Text)

[img]http://www.healingcrystalshealingstones.com/images3/Albitehealingcrystals.jpg[/img]
1. What is the chemical formula for this mineral?
2. What is this specific variety of this mineral called?
3. What kind of cleavage does this mineral display?
4. Name two minerals this mineral commonly occurs in conjunction with.
5. Name one use this mineral has in industry

1. NaAlSi3O8
2. Albite (plagioclase group/albite-anorthite series)
3. Tabular
4. (groups) K-spar and quartz
5. Useful in the manufacturing of ceramics

4/5. I was looking for "perfect, good, imperfect" for cleavage, or, if you are really savvy with 3D coordinates, "Perfect on [001], good on [010], imperfect on {110}" as defined by http://www.mindat.org, I believe that "tabular" is more of the habit shown here. Very good!

Your turn.

I will mention that typically (at least from what I remember) when tests ask for cleavage they want the type of cleavage, such as basal, cubic, rhombohedral, etc. rather than the quality of cleavage (perfect, good). Tabular would still be incorrect, just putting my input.

[dxu46]

[b]Question[/b] (Click to Show Hidden Text)

[img]http://www.healingcrystalshealingstones.com/images3/Albitehealingcrystals.jpg[/img]
1. What is the chemical formula for this mineral?
2. What is this specific variety of this mineral called?
3. What kind of cleavage does this mineral display?
4. Name two minerals this mineral commonly occurs in conjunction with.
5. Name one use this mineral has in industry

1. NaAlSi3O8
2. Albite (plagioclase group/albite-anorthite series)
3. Tabular
4. (groups) K-spar and quartz
5. Useful in the manufacturing of ceramics

4/5. I was looking for "perfect, good, imperfect" for cleavage, or, if you are really savvy with 3D coordinates, "Perfect on [001], good on [010], imperfect on {110}" as defined by http://www.mindat.org, I believe that "tabular" is more of the habit shown here. Very good!

Your turn.

Oops, I read it as "crystal growth."

Question (Click to Show Hidden Text)

[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS5jSk8PTl0jkYUJoO7U3mS4YNYMr4pDUidpOz0D-FOLO4bZ0fkGg[/img]
(in real life this rock would have shiny particles)
1. Identify this rock.
2. How did it form?
3. What are the main minerals that constitute this rock?
4. What is the texture of this rock?

[whythelongface]

Question (Click to Show Hidden Text)

[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS5jSk8PTl0jkYUJoO7U3mS4YNYMr4pDUidpOz0D-FOLO4bZ0fkGg[/img]
(in real life this rock would have shiny particles)
1. Identify this rock.
2. How did it form?
3. What are the main minerals that constitute this rock?
4. What is the texture of this rock?

1. Mica schist
2. Continued heat/pressure metamorphism of phyllite
3. Quartz, mica, feldspar, chlorite, talc, etc.
4. Foliated

[whythelongface]

I will mention that typically (at least from what I remember) when tests ask for cleavage they want the type of cleavage, such as basal, cubic, rhombohedral, etc. rather than the quality of cleavage (perfect, good). Tabular would still be incorrect, just putting my input.

Thank you. I should have been clearer: what is the quality of the cleavage? Since many minerals do not strictly have perfect rhomb, cubic, basal cleavage...

[dxu46]

Question (Click to Show Hidden Text)

[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS5jSk8PTl0jkYUJoO7U3mS4YNYMr4pDUidpOz0D-FOLO4bZ0fkGg[/img]
(in real life this rock would have shiny particles)
1. Identify this rock.
2. How did it form?
3. What are the main minerals that constitute this rock?
4. What is the texture of this rock?

1. Mica schist
2. Continued heat/pressure metamorphism of phyllite
3. Quartz, mica, feldspar, chlorite, talc, etc.
4. Foliated

Correct! Your turn!

[whythelongface]

Question (Click to Show Hidden Text)

[img]http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/24378det.jpg[/img]
A longer question than usual:
1. What is the clear mineral's chemical formula?
2. What kind of fracture does this mineral have?
3. What is the chemical formula of the red specks?
4. What is the red mineral's crystal system?
5. How did the red mineral end up inside the clear mineral?
6. Note the small purple triangle slightly lower right of the center of the picture. What is this formation called?
7. Suppose this crystal came out of a geode. Would I expect to see similar crystals throughout the entire geode?

[dxu46]

Question (Click to Show Hidden Text)

[img]http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/24378det.jpg[/img]
A longer question than usual:
1. What is the clear mineral's chemical formula?
2. What kind of fracture does this mineral have?
3. What is the chemical formula of the red specks?
4. What is the red mineral's crystal system?
5. How did the red mineral end up inside the clear mineral?
6. Note the small purple triangle slightly lower right of the center of the picture. What is this formation called?
7. Suppose this crystal came out of a geode. Would I expect to see similar crystals throughout the entire geode?

1. SiO2
2. Conchoidal
3. Fe2O3
4. Hexagonal
5. Exsolution?
6. Not sure...pleochroism from fracture?
7. Yes?

P.S. Really cool picture. Better than other ferroginous quartz.

[whythelongface]

Question (Click to Show Hidden Text)

[img]http://www.johnbetts-fineminerals.com/jhbnyc/mineralmuseum/24378det.jpg[/img]
A longer question than usual:
1. What is the clear mineral's chemical formula?
2. What kind of fracture does this mineral have?
3. What is the chemical formula of the red specks?
4. What is the red mineral's crystal system?
5. How did the red mineral end up inside the clear mineral?
6. Note the small purple triangle slightly lower right of the center of the picture. What is this formation called?
7. Suppose this crystal came out of a geode. Would I expect to see similar crystals throughout the entire geode?

1. SiO2
2. Conchoidal
3. Fe2O3
4. Hexagonal
5. Exsolution?
6. Not sure...pleochroism from fracture?
7. Yes?

P.S. Really cool picture. Better than other ferroginous quartz.

Allow me to explain the background on this picture.
This is no ordinary ferruginous quartz. This is a specimen of Brandberg amethyst, which is famous for its inclusions, including hematite, liquid, and gas inclusions. The purple formation is known as a phantom, and it is amethyst quartz. Phantoms form when a period of growth ends, and the chemical nature of the surroundings change. Perhaps the solution was more iron rich initially, but when the iron ions were depleted, the crystal became clear.

Everything else appears to be correct. For 5, I was looking for something just that answers the question just a tad better, i.e. exsolution during growth. This is because exsolution can occur after the quartz has completely formed, resulting in a layer of hematite on the surface of the crystal and not necessarily incorporated into it.

Good job. Your turn!

P.S.: here is another Brandberg amethyst, with more clearly defined phantoms. Hopefully you can see that these were once crystal surfaces that got overgrown during changes in solution chemistry.

[dxu46]

Wow....

Question (Click to Show Hidden Text)

[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS48r4oJV9_fL8ZbD1-_mtL1xavLxEilz4ZHiWjYx6s4nPvF4If[/img]
Just ID (variety, not group)

[whythelongface]

Wow....

Question (Click to Show Hidden Text)

[img]https://encrypted-tbn0.gstatic.com/images?q=tbn:ANd9GcS48r4oJV9_fL8ZbD1-_mtL1xavLxEilz4ZHiWjYx6s4nPvF4If[/img]
Just ID (variety, not group)

Oh no...

Guess (Click to Show Hidden Text)

It looks like it's probably an emerald, although I've seen some tremolite that occurs in that shade of green.