Rocks and Minerals Question Marathon

[iYOA]

revive!!

Question 12 (Click to Show Hidden Text)

[img]http://webmineral.com/specimens/photos/Albite1Small.jpg[/img]
a)Identify it
b) Chemical composition?

The picture isn't loading for me.. and I just saw the link when quoting :X

whoops sorry I guess I'll sit out this one

You can still answer if you want as long as you explain why the id makes sense because this marathon is dying

[Wadhk]

Possible? (Click to Show Hidden Text)

Biotite 
K(Mg, Fe+2)3  (Al, Fe+3) Si3 O10 (OH,F)2

[iYOA]

well, biotite is typically a very dark color and it doesnt occur fanned out like in the image. so try again

[sparky007]

How do I hide an answer?

[iYOA]

you click on the hide button should get:
[hide][/hide]

then follow this format
[ hide] Name of the button | text that is supposed to be hidden [/hide ]

note that i put a space between the first bracket and the h and a space between the very last bracket and the e so that it wouldnt actually hide

[tornado guy]

To revive this thread.. Here is an easy one. which rock is this? And what type of rock?

Happy Guessing! (Click to Show Hidden Text)

[img]http://upload.wikimedia.org/wikipedia/commons/7/7e/RhyoliteUSGOV.jpg[/img]

[XXGeneration]

Answer? (Click to Show Hidden Text)

Andesite? It would be an igneous rock if it were andesite.

[tornado guy]

Answer? (Click to Show Hidden Text)

Andesite? It would be an igneous rock if it were andesite.

You got the igneous part right! But the rock name is wrong.
EDIT: Here's a hint: The mineral assemblage is usually quartz, alkali feldspar and plagioclase.

[quizbowl]

from the description, maybe a rhyolite?

[tornado guy]

from the description, maybe a rhyolite?

Yes! Your turn.