PROBLEM SET 2

                                          Still more practice problems


1. Given the following mineral formulas determine the valence ( charge and number ) of the element labeled "X" in each formula below.

              a.  Al6XPO4(OH)8.2H2O         b.  X3Al2Si6O18                      Given: P = +5

              c  KAlX3O8               d.  Mg3X2Si3O12      e.  CaAl2X2( Al2Si2O10 )

 

2.  Given the following element oxide information below, determine the formula of the mineral.  The ratio x:y of (OH)X and yH2O = 6:5 in the formula.  Factoring during the problem is important. Fill in the formula in the blank space below.

               formula with all water as YH2O                                        = Na2O + 2CaO + 5B2O3 + 16H2O

 

3. Calculate the weight percent of each element (cation) oxide for the mineral formula below.  Show and organize your work.

          Cu3SO4(OH)4        Cu = +2,  S = +6

 

4. Given the following element (cation) oxide weight percents, determine the formula of the mineral.  The  formula consists of all the water in the mineral calculated as yH2O.  Show and organize your work.

         MgO = 31.7%,  H2O = 4.8%, SiO2 = 63.5%

 

5. Answer a and b below;

           a. determine the parameters ( face intercepts) of a  single face constituting a form which intersects the crystallographic axes at the following distances measured from the vortex of the unit cell of the mineral.

                  distances of intercept of axes from vortex:  a = (minus coordinate intercept)2.56 ; b = 35.72;  c = 7.37 

                  unit cell dimensions measured from same vortex:  a = 5.13 ;  b = 8.93 ;  c = 7.37 ;

            b.  determine the Miller Indices for the parameters in a, above 

 

6. Given the following parameters of a single face of a form (face intercepts), determine the Miller Indices of each face below

          a.  2a(minus): 3b: 3c   b.  1/2a: 1/4b(minus): infinityc     c. 6a: 1/4b: 3c(minus)

 

7.  Given the following information below, determine the S.G. of  the mineral aragonite, ( CaCO3).  Show and organize your work.  

            SG = M x Z/ N x V            Z = 4     N = 6.02 x 1023 ;   a = 4.96    b = 7.97    c = 5.74 

 

8.  Answer the following below;

        a. how many faces comprise a?;

            1. ditrigonal pyramid      2.  hextetrahedron    3. pyritohedron   4. dihexagonal prism  

        b.  state the number of atoms of each element associated with the unit cell of the mineral with the empirical formula, Cu3SO4(OH)             Z = 4 

        c.  state the name of each of the following cation oxides;

             1.  K2O     2.  Na2O   3.  CaO

        d.  state the name of each unit cell below having the specific arrangement of (nodes) atoms;

             1.  a (node) atom located at each corner but not on faces nor at very center of the unit cell

             2. a (node) atom located at each corner and at each face on the c axis

             3. "     "         "        "     "        "        "  at the very center of the unit cell, but not on any faces

        e. State the name of the holohedral crystal class in each of the following crystal systems or divisions;

                           1. monoclinic,   2.  tetragonal,   3.  hexagonal  rhombohedral,   4. isometric    

 

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