Sinter

Sinter, the name given by German mineralogists to those rocks which are precipitated in a crystalline form from mineral waters. Sinter is of various forms, kidney-shaped, knotted, tuberous, botryoidal, tubular, stalactitic, shrub-like, or pronged, and is occasionally distinguished by its chief component, as Calc-sinter, Siliceous sinter, Iron-sinter, &c. Calc-sinter, which is a variety of carbonate of lime, composed of concentric plane parallel layers, appears under various forms; it is deposited with extraordinary rapidity by many springs, a peculiarity frequently made use of to obtain the incrustation of objects with a coating of this substance. Siliceous sinter is mostly found in intermittent hot springs, as in the Geysers (q.v.) of Iceland. Iron-sinter occurs in old mines and in coal-beds, where it is formed from iron pyrites through the agency of the atmosphere. The tubular conglomeration of grains of sand half-melted by lightning (blitz) is also known as Blitz-sinter, or Fulgurite (q.v.).