and how are silicate minerals and nonsilicate minerals alike?
Most rock forming minerals are silicates BUT there are several rock forming minerals which are not silicates. Examples of such minerals are calcite, dolomite, apatite, fluorspar, gypsum, the spinel series graphite. Generally, non silicate minerals separate out from silicates in melts or in hydrothermal solutions. Because of their different chemistry, they don't want to associate together therefore segregate. Silicate non silicate minerals have the similarity that they are naturally forming inorganic substances that are solids at room temperature, vary in their chemistry only within natural constraints (such as Fe content within sphalerite, that is composed predominantly of zinc sulphide, or the variable Fe Mg contents within olivine, that is an iron magnesium silicate).
