Of the 3 main classes of rock, this one accounts for about 75% of all the exposed rocks on land
These are very common in arid lands, where seasonal "playa lakes" 
occur in... [DOC] [TLE] sedimentary rock | Britannica.com [PAR] Sedimentary rocks are the most common rocks exposed on the Earth's surface ... 
and two fundamentally different kinds of sediment and sedimentary rock: (1) ... 
and sedimentary rock comprises 75 percent of the land surface and well over 90 
.... that only three varieties account for the bulk of all sedimentary rocks: mudrock,
... [DOC] [TLE] Minerals, Rocks & Rock Forming Processes [PAR] These 9 minerals are all silicates, and are also called the rock forming minerals.