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GEOLOGY 1008             NAME:

EXERCISE 3 - IGNEOUS ROCKS

Step 1: Identify the properties of the rocks (mineral composition, grains observed, and texture) using the instructions provided in the lab book. You should use a hand lens to examine the rocks; the mineral grains will be much easier to see.

Step 2: Determine if the rock is intrusive or extrusive.

Step 3: Determine each rock's identity. Answer the questions at the end of the table and in the book (see course outline).

ROCK # MINERAL
COMPOSITION
(p. 40-41)		 mineral grains observed (if any)
(use the table on p. 41)		 TEXTURE
(see p 39-40)		 intrusive/
extrusive		 ROCK NAME
(use the table on p.42)

I 1


   none seen      

I 2


 intermediate  plagioclase & maybe augite or hornblende  fine & porphyritic   extrusive  porphyritic andesite

I 3


         

I 4


         

I 5


         

I 6


         

I 7


         

I 8


     pegmatitic    

I 9


     fine & porphyritic    

I 10


     coarse & porphyritic    

I 11


 ultramafic        

I 12


 N/A (glassy)    glassy & vesicular    

I 13


         

1 14


 N/A (glassy)        

Compare the following rocks, how are they similar, how do they differ, why?

GRANITE and RHYOLITE:

 

GRANITE, DIORITE, and GABBRO:

 

Back to lab 3 help.

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