Question

Using Table 22.1, predict the structure of each of the following silicate minerals (network, sheets, double chains, and so forth). Give the oxidation state of each atom.

1. Tremolite,${\mathbf{Ca}}_2{\mathbf{Mg}}_5{\left({\mathbf{Si}}_2{\mathbf{O}}_{11}\right)}_2{\left(\mathbf{OH}\right)}_2$
2. Gillespite,${\mathbf{BaFeSi}}_4{\mathbf{O}}_{10}$
3. Uvarovite,${\mathbf{Ca}}_3{\mathbf{Cr}}_2{\left({\mathbf{SiO}}_4\right)}_3$
4. Barysilate,${\mathbf{MnPb}}_8{\left({\mathbf{Si}}_2{\mathbf{O}}_7\right)}_3$

Short answer

1. Infinite double chain silicates.
2. Infinite sheets.
3. Silicate tetrahedra.
4. Pairs oftetrahedra.

Step-by-step solution

Silicates

The most abundant elements on earth‘s crust are oxygen and silicon. The bond between Si-O is strong and has a partial ionic character. They form the basis for the class of minerals called silicates.

Subpart (a)

The given silicate is tremolite. The repeating unit is$S{i}_4{O_{11}}^{6-}$ . It comes under the class of double chain silicates.

The oxidation number of Mg is +2, Ca is +2, Si is +4, and O is -2.

Subpart (b)

The given silicate is Gillepsite. The repeating unit is$S{i}_4{O}_{10}$ .It comes under infinite sheets.

The oxidation state of Ba is +2, Fe is +2, Si is +4 and O is -2.

Subpart (c)

The given silicate is Uvarovite. It is an example of silicate tetrahedral. The repating unit is $Si{O_4}^{4-}$.

The oxidation state of Ca is +2, Cr is +3, Si is +4 and O is -2.

Subpart (d)

The given silicate is barysilate. The repeating unit is .$S{i}_2{O_7}^{6-}$ It is an example of pairs of tetrahedral silicate.

The oxidation state of Mn is +2, Pb is +2, Si is +4 and O is -2.