Lithology and Its Bearing on Water Composition

The composition of rocks and soils has a direct bearing on the quality of water. Hydrochemically a rough classification into three rock groups seems practical  

The lithological parameter is only one of several parameters that control groundwater quality. Other factors include evaporation at the surface prior to infiltration, transpiration, wash-down of sea spray, and reducing conditions in the aquifer, connected to H2S production. Water moves underground, and its salt or mineral content is determined by all soil and rock types it passes through. Thus, occasionally, saline water may be encountered in rocks that by themselves do not contribute soluble salts. 

1 Rocks that Preserve High Water Quality 

Pure sandstone, rich in quartz grains and with little or no cement, may host very fresh water with little addition to the salts brought in by recharging rain (Table 3.1). Other rocks hosting fresh water are quartzite (sandstone 

Marcel Dekker, Inc. 270 Madison Avenue, New York, New York 10016 

---