Re: Rocks & Minerals B/C
Posted: March 25th, 2013, 1:17 pm
2 minutes per question or 2 minutes per station? (and how many questions per station? Regionals was on average 2 questions per station, but state should be more, right?)
Satin-spar Gypsum is softer (you can scratch it with your fingernail) and the striations are duller.SciJ wrote:I have a couple of ID questions:
How do you differentiate between satin-spar and a ulexite that does not show its optic fiber property? How do you identify a non-hexagonal beryl? And is crystalline limestone just a limestone with visible crystals?
Thanks! So, what is crystalline limestone then?piimasta314 wrote:Satin-spar Gypsum is softer (you can scratch it with your fingernail) and the striations are duller.
For beryl, there's lots of identifying factors besides crystal shape...you can use the luster, fracture/cleavage, etc.
Crystalline limestone doesn't always have to have visible crystals.
Sorry, that last one wasn't very clear. Crystalline limestone is when CaCO3 recrystallizes in limestone that was already there. But sometimes the CaCO3 crystals are so small or just so dull that they're not easily visible. You can google some pictures. A lot of crystalline limestone is pretty dull and ugly, and you can't really see the crystals too well, but you might be able to find them through magnification.SciJ wrote:Thanks! So, what is crystalline limestone then?piimasta314 wrote:Satin-spar Gypsum is softer (you can scratch it with your fingernail) and the striations are duller.
For beryl, there's lots of identifying factors besides crystal shape...you can use the luster, fracture/cleavage, etc.
Crystalline limestone doesn't always have to have visible crystals.
It doesn't matter where I got it from, because at regionals, my teammate found a stash of rocks & minerals a school obviously dumped onto the dirt (who knows why?). Well there was about 10 of us digging through snow and weeds finding topaz, jasper, many quartz, etc. Like I said before, I can answer questions about its physical properties.piimasta314 wrote:There's a lot of cool looking minerals encrusted on this rock. I don't know what the white stuff is from the picture alone...Where did you find it?