Rocks & Minerals B/C

sofossils
Member
Member
Posts: 61
Joined: September 28th, 2011, 5:05 pm
Division: Grad
State: PA

Re: Rocks & Minerals B/C

Postby sofossils » February 5th, 2013, 12:42 pm

Does anyone know how to tell apart Malachite, Olivine, and Epidote when in massive and unpolished form?
Assistant Coach of AHSO
Yale University '21

User avatar
paleonaps
Exalted Member
Exalted Member
Posts: 1282
Joined: March 7th, 2009, 7:14 am
Division: Grad
State: NY
Location: Turning and turning in the widening gyre

Re: Rocks & Minerals B/C

Postby paleonaps » February 17th, 2013, 1:50 pm

Hi! Remember me?
I was just looking through the wiki and I saw that it has Opal and Quartz as Oxides. However, the Simon and Schuster guide, the Internet (i.e. Wikipedia), and my memory say that they are actually Silicates. I changed it on the wiki, but I figured I'd ask if it was a mistake or if they were reclassified or something. I just want to make sure that it's accurate.
Brown University 2017
2009 B Division National Ecology Champion
4 time National Medalist
Farewell Science Olympiad. We will meet again.

User avatar
aim4me26
Member
Member
Posts: 96
Joined: April 26th, 2012, 3:58 pm
Division: Grad
State: CA
Location: looking pretty in a hotel bar

Re: Rocks & Minerals B/C

Postby aim4me26 » February 17th, 2013, 3:49 pm

Hi! Remember me?
I was just looking through the wiki and I saw that it has Opal and Quartz as Oxides. However, the Simon and Schuster guide, the Internet (i.e. Wikipedia), and my memory say that they are actually Silicates. I changed it on the wiki, but I figured I'd ask if it was a mistake or if they were reclassified or something. I just want to make sure that it's accurate.
Lol, hi Naps. And yeah, I think you're right.
i know that i should be in bed
and its almost 3 am
but when i close my eyes i can only see miles of headlights
fleshing out the distance

allisonc524
Member
Member
Posts: 7
Joined: February 7th, 2013, 6:49 pm
Division: C
State: NM

Re: Rocks & Minerals B/C

Postby allisonc524 » February 22nd, 2013, 2:03 pm

So, I've got state tomorrow, and was just told today that I'm on rocks and minerals. What can I study in that short amount of time? No one expects me to do well, but I'm hoping I might surprise my team...
Events:
Forensics: Invitationals: 4th State: 1st
Forestry: Invitationals: 4th State: (unable to compete) My partner made 7th though!

Skink
Exalted Member
Exalted Member
Posts: 947
Joined: February 8th, 2009, 12:23 pm
Division: C
State: IL

Re: Rocks & Minerals B/C

Postby Skink » February 22nd, 2013, 5:01 pm

Maybe either...

1. Try to learn to identify by sight a few obscure minerals your partner may not know e.g. kaolinite, sphalerite...

2. Try to make sense of Bowen's reaction series and Moh's hardness scale. These are effectively reading charts, so you could try to quickly get really familiar with these and ignore sample ID, which your partner should be well prepared for at this point. You could throw in crystal systems if you wanted to, but that's less important in a time crunch.
Hi! Remember me?
I was just looking through the wiki and I saw that it has Opal and Quartz as Oxides. However, the Simon and Schuster guide, the Internet (i.e. Wikipedia), and my memory say that they are actually Silicates. I changed it on the wiki, but I figured I'd ask if it was a mistake or if they were reclassified or something. I just want to make sure that it's accurate.
Look at the chemical formulas. Quartz is easy, SiO2, and, looking up opal, it's derived from that. The silicate Wiki page says silicates are SiO4 tetrahedra and that, for that reason, SiO2 is sometimes classified as a silicate. Calling it an oxide will never completely be wrong because it IS an oxide. Whether grouping it as 'silicate' is more correct or not, well, the jury's still out, it seems.

User avatar
kalithepianist
Member
Member
Posts: 31
Joined: December 30th, 2010, 10:00 am
Division: C
State: AZ
Location: That one place.

Re: Rocks & Minerals B/C

Postby kalithepianist » February 23rd, 2013, 4:58 pm

can somebody explain Bowen's Reaction Series? i can't really find a simple explanation for it and i'm not really seeing how it's helpful for this event .___.
derp

User avatar
tuftedtitmouse12
Member
Member
Posts: 778
Joined: January 3rd, 2011, 12:26 pm
Division: Grad

Re: Rocks & Minerals B/C

Postby tuftedtitmouse12 » February 23rd, 2013, 8:07 pm

Hi! Remember me?
I was just looking through the wiki and I saw that it has Opal and Quartz as Oxides. However, the Simon and Schuster guide, the Internet (i.e. Wikipedia), and my memory say that they are actually Silicates. I changed it on the wiki, but I figured I'd ask if it was a mistake or if they were reclassified or something. I just want to make sure that it's accurate.
Lol, hi Naps. And yeah, I think you're right.
Will second it...too lazy to hunt down my rocks field guide floating around somewhere.
peter, peter, peter

User avatar
quizbowl
Member
Member
Posts: 1044
Joined: April 10th, 2010, 3:48 pm
Division: Grad
State: NY
Location: Syosset High, WLI, NY --> UChicago '16

Re: Rocks & Minerals B/C

Postby quizbowl » February 24th, 2013, 2:19 pm

can somebody explain Bowen's Reaction Series? i can't really find a simple explanation for it and i'm not really seeing how it's helpful for this event .___.
So imagine I'm a big ol' volcano. RAWR I GOTS MAGMA.
Discontinuous: When magma cools, the minerals that form will form in a very specific way. First olivine forms at the hottest temperature, and as the temperature goes lower, new minerals start to form (pyroxene-> amphibole -> biotite). Eventually, at a very cool ~850C, it forms orthoclase, muscovite and quartz. It's pretty helpful - you can tell that rocks that are mafic tend to form at hotter temperatures than felsic rocks, and the respective minerals in each correspond to their position on the reaction series. By the logic, you'll never find a typical igneous rock containing both olivine and quartz crystals (unless something funky is going on).

Continuous:: Along similar lines, but we're looking at the Ca/Na ratio of the magma (mafic contains lots of calcium, intermediate contains lots of sodium). Essentially, at the highest temperatures it'll be rich in Ca-feldspar, and as you cool, you'll have more Na-feldspar. It also converges to the orthoclase-muscovite-quartz point.

If you understand how the Bowen's Reaction Series works, you can figure out why there is differentiation among igneous rocks.
2010: 5th in NYS
2011: 4th in NYS
2012: 3rd in NYS
<quizbowl> ey kid ya want some shortbread
<EASTstroudsburg13> I don't know why, but I just can't bring myself to delete this post.

zimmy1235
Member
Member
Posts: 12
Joined: February 27th, 2012, 5:31 pm
Division: C
State: PA

Re: Rocks & Minerals B/C

Postby zimmy1235 » February 26th, 2013, 6:06 pm

I'm looking at chert and chalcedony, and was wondering if someone could explain the terms microfibrous and microcrystalline, and possibly cryptocrystalline as I don't totally get their difference and how they apply to each of the previous specimens.

Shad160
Member
Member
Posts: 126
Joined: March 7th, 2009, 3:32 pm
Division: Grad
State: NY
Location: Hicksville -> URochester '17

Re: Rocks & Minerals B/C

Postby Shad160 » February 26th, 2013, 6:18 pm

I'm looking at chert and chalcedony, and was wondering if someone could explain the terms microfibrous and microcrystalline, and possibly cryptocrystalline as I don't totally get their difference and how they apply to each of the previous specimens.
From my understanding, microcrystalline describes a crystal habit that is minuscule and only visible through a microscope, microfibrous is a fibrous crystal habit that can only be viewed under a microscope, and cryptocrystalline has a crystal habit that can only be viewed through polarized light (and a microscope, at that). They're all relatively minute differences, term-wise.

For their role in Chert and Chalcedony, the terms are just used to describe the different varieties that are possible for the crystals

(I've also only been on this event for <1 month, so if someone has a better understanding please feel free to chime in)
What happens on Alpha Lyrae, stays on Alpha Lyrae.


Return to “2013 Study Events”

Who is online

Users browsing this forum: No registered users and 1 guest