Rocks and Minerals B/C

[SciBomb97]

I'm pretty sure I've heard it for both... But to be on the safe side, I'd go with gneiss's info...

Actually, everyone so far is wrong! Jasper is a form of Chalcedony.

You got that from Wikipedia, didn't you? Different Wikipedia pages seem to be conflicting on this... THIS page says that jasper is a variety of chert under the "Varieties of Chert" heading while THIS page says that it's a variety of chalcedony while THIS page says that jasper, chalcedony, and chert are all just different forms of microcrystalline quartz under the "Varieties (according to microstructure)" subheading.
In fact, chert, chalcedony, and jasper are all just different forms of quartz. Of that I am sure.

[quizbowl]

I'm pretty sure I've heard it for both... But to be on the safe side, I'd go with gneiss's info...

Actually, everyone so far is wrong! Jasper is a form of Chalcedony.

You got that from Wikipedia, didn't you? Different Wikipedia pages seem to be conflicting on this... THIS page says that jasper is a variety of chert under the "Varieties of Chert" heading while THIS page says that it's a variety of chalcedony while THIS page says that jasper, chalcedony, and chert are all just different forms of microcrystalline quartz under the "Varieties (according to microstructure)" subheading.
In fact, chert, chalcedony, and jasper are all just different forms of quartz. Of that I am sure.

Not really. Chalcedony is really an amalgamation of both quartz and mogamite. While both are SiO2, mogamite is really a polymorph of quartz. Yes, it is a silica mineral, but I personally don't consider it a variety of quartz. However, the list trumps all interpretation, so while we might argue for days on end over the true chemical nature of these minerals, the list is all that counts.

[crazyfloboe]

Werll, accordiong to the offical list for Nats 2012. Its Quartz, and im trusting that list and that list only.

[LoopQuantumGravity]

Source:http://webmineral.com/data/Quartz.shtml
According to this, jasper is red or brown chalcedony.
Chalcedony is microcrystalline quartz. Also, other sources have said that it also contains moganite (a monoclinic silica mineral)
Chert is similar, only it is cryptocrystalline (smaller crystals).

[gneissisnice]

Source:http://webmineral.com/data/Quartz.shtml
According to this, jasper is red or brown chalcedony.
Chalcedony is microcrystalline quartz. Also, other sources have said that it also contains moganite (a monoclinic silica mineral)
Chert is similar, only it is cryptocrystalline (smaller crystals).

Chalcedony is microcrystalline and chert/flint is cryptocrystalline. What that means that is that chalcedony has tiny crystals, while chert has crystals so small that you can't see them at all, making it look more like there aren't any.

I always learned that jasper was red or brown chert, not chalcedony, but I suppose there's still some grey area there. Easier just to say that jasper is red micro- or cryptocrystalline quartz and call it a day.

[10manwire]

Hello! I was wondering if any of you knew what Barite (Baryte) typically looks like. I've seen many pictures of it, and none of them seem characteristic or all that similar. Thank you!

[Allinea]

Hello! I was wondering if any of you knew what Barite (Baryte) typically looks like. I've seen many pictures of it, and none of them seem characteristic or all that similar. Thank you!

I've never had a barite sample on a test, but from pictures I'd say either a dirtied yellow-green, sometimes orange (not like sulfur, which is more lemon or bright yellow), or translucent or white with a shape kinda like calcite, but a bit flatter? I'd say the main characteristic to look for is the shape (looks kinda like calcite, to me at least), and if the color matches. You'll be able to tell the difference between clear barite and calcite because calcite has double refraction, barite doesn't. Does that help at all?

[10manwire]

I've never had a barite sample on a test, but from pictures I'd say either a dirtied yellow-green, sometimes orange (not like sulfur, which is more lemon or bright yellow), or translucent or white with a shape kinda like calcite, but a bit flatter? I'd say the main characteristic to look for is the shape (looks kinda like calcite, to me at least), and if the color matches. You'll be able to tell the difference between clear barite and calcite because calcite has double refraction, barite doesn't. Does that help at all?

Yeah, that kind of does. Thank you!

[pjgscioisamazing]

I've never had a barite sample on a test, but from pictures I'd say either a dirtied yellow-green, sometimes orange (not like sulfur, which is more lemon or bright yellow), or translucent or white with a shape kinda like calcite, but a bit flatter? I'd say the main characteristic to look for is the shape (looks kinda like calcite, to me at least), and if the color matches. You'll be able to tell the difference between clear barite and calcite because calcite has double refraction, barite doesn't. Does that help at all?

Yeah, that kind of does. Thank you!

Also, a big hint is the specific gravity. If you have a non metallic mineral that isn't a blue crystal, and it feels quite heavy, chances are it's barite.

[quizbowl]

So from what I heard, nationals (for C, at least) was a debacle. First of all, UPS lost all of the mineral samples, so they resorted to using "descriptions" for those stations. And speaking of stations, there were only six - each was eight minutes long with about twenty questions, and a lot were true/false. Look, I might be no national coordinator, but it's quite obvious that ID events were created to be quick-paced with short, crammed stations. I understand the issue with the minerals, but the entire setup sounds disappointing. Not what I'd expect from a Nationals competition. I hope that in the next few years the Rocks and Minerals event can be run much more smoothly.