GEOCHEMISTRY

GEOL 5063

Test 1

October 5, 2001

 

Be sure to show all of your work.  Illustrations and sketches are encouraged, but be sure to label them completely.  Answer any six questions.  Each question is worth 18 points for a total of 108 points.

 

1.  Place the following elements in order of their abundance in the earth’s crust and explain your choices.

 

                        Rb, Sr, Cr, Fe

 

2.  What is the predicted sequence of removal of the following elements from an aqueous solution containing clay minerals.  Explain why you have chosen this sequence.

 

Ca, Sr, Li, Cs

 

3.  An ammonia (NH3) analysis of water reports a concentration of 0.01 mg/L as nitrogen.  What is the concentration in terms of ammonia?

 

4.  What is the sequence of ionic substitution of the following metals in olivine (Mg2SiO4) ?  Why?

 

                        Cr3+, Co2+, Ni2+, Cu2+

 

5.  Describe the formation of perthite.

 

6.  At a pH of 12, what is the most abundant carbonate ion?  Why?  What is the ratio of this ion to the next most abundant carbonate ion?

 

7. Discuss the substitution of the following for one another in igneous minerals.

 

                        Zr, Hf, Si,

 

 

Useful information?

               

                               (H+) (CO32-)

              10 -10.3 =  ----------------

                                  (HCO3-)                                               

 

 

                                 (H+) (HCO3-)                                                                                                        

                10 -6.4 =     ---------------                         

                                    (H2CO3)