Weathering of mineral deposits

Vinegar is recommended for cleaning a variety of appliances and other items that may be stained by hard water deposits. Automatic coffee makers, steam irons, dishwashers, teapots, faucet heads, and shower heads — over time, all accumulate calcium deposits from hard water. Groundwater, that is, water that travels through soil and rocks, accumulates dissolved calcium ions as a consequence of the natural weathering of minerals that contain calcium such as limestone and calcite, shells, and coral. At the same time, carbon dioxide in the air dissolves in water to form carbonate ions that combine with calcium ions to form a white solid, calcium... 

Role of microscopic fungi in the process of weathering of pegmatite deposit rocks and minerals. Mikrobiologiya, 50, 156-62. 

A few minerals produce acid when they contact water. These minerals can be described as salts of weak bases and strong acids. They chiefly result from weathering and oxidation of the pyrite or marcasite (FeS2) exposed in the mining of mineral deposits and coal. Such acid minerals, which are dominantly Fe sulfates and to a minor extent AP sulfates, typically form from the evaporation of pooled acid-mine waters or of the moisture in unsaturated mine wastes or spoils that contain the sulfides. Acidity is produced when they are dissolved by fresh runoff or recharge. For example... 

Table 5.7. Common Secondary Phosphate Minerals Formed During the Weathering of Phosphate Deposits...

Plumbonacrite is a rare basic lead carbonate mineral with composition Pbio(C03) 0(OH)g. Named for its composition and pearly lustre, it was first described by Heddle in 1889 from Wanlockhead (Scotland) it has also been reported to occur at Tiger (Arizona, USA). Plumbonacrite is not well characterised as a mineral and is considered to be a metastable phase, converting readily to hydro-cerussite and cerussite qq.v. Haacke and WiUiams, 1981). It forms as a secondary mineral via the weathering of lead deposits and as a corrosion product of lead objects, forming as an intermediate phase of lead and lead oxide carbonitisation, as noted by Olby (1966). The structure of synthetic plumbonacrite has been characterised recently by Krivovichev and Bums (2000), who give the composition as Pb50(0H)2(C03)3. 

The extremely deep bio-weathering in the Amazon system has produced many important and new types of mineral deposits. In regions of intense and deep leaching, the input of many chemical species may be dominated by rain and aerosols. 

---