In addition, quartz and gibbsite also dissolved by in much smaller concentrations and over greater spans of time. The feldspars and many of the dark silicate minerals dissolve and undergo hydrolysis, the reaction of a mineral with water. These reactions are incongruent in that there is a new solid phase produced by the reaction. O 8 Albite Feldspar Kaolinite Clay Hydrolysis reactions also involve organic compounds. In this case an organic molecule reacts with water forming a new organic molecule and several ions.
Some organic compounds are susceptible to hydrolysis.
These precipitates, such as calcite and siderite deposition may result in massive formations such as stalactites, stalagmites, columns, flowstones, and travertine mounds. Quartz deposition in hot springs may form massive siliceous sinter deposits. Gypsum, and other evaporites, deposition may result in the formation of large crystals in evaporating lakes and seas. All of these are types of precipitation. However, cementation, one of the processes that turns sediments into rocks, is also a precipitate.