Rotten stone, sometimes spelled as rottenstone, also known as tripoli, is fine powdered porous

rock Rock most often refers to: * Rock (geology), a naturally occurring solid aggregate of minerals or mineraloids * Rock music, a genre of popular music Rock or Rocks may also refer to: Places United Kingdom * Rock, Caerphilly, a location in Wale ...

used as a

polishing Polishing is the process of creating a smooth and shiny surface by rubbing it or by applying a chemical treatment, leaving a clean surface with a significant specular reflection (still limited by the index of refraction of the material accordi ...

abrasive An abrasive is a material, often a mineral, that is used to shape or finish a workpiece through rubbing which leads to part of the workpiece being worn away by friction. While finishing a material often means polishing it to gain a smooth, reflec ...

for metal smithing, historically for the grinding of optical lenses and in

woodworking Woodworking is the skill of making items from wood, and includes cabinetry, furniture making, wood carving, joinery, carpentry, and woodturning. History Along with stone, clay and animal parts, wood was one of the first materials worked b ...

. It is usually weathered

limestone Limestone is a type of carbonate rock, carbonate sedimentary rock which is the main source of the material Lime (material), lime. It is composed mostly of the minerals calcite and aragonite, which are different Polymorphism (materials science) ...

mixed with

diatom A diatom (Neo-Latin ''diatoma'') is any member of a large group comprising several Genus, genera of algae, specifically microalgae, found in the oceans, waterways and soils of the world. Living diatoms make up a significant portion of Earth's B ...

aceous, amorphous, or crystalline

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , commonly found in nature as quartz. In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant f ...

. It has similar applications to

pumice Pumice (), called pumicite in its powdered or dust form, is a volcanic rock that consists of extremely vesicular rough-textured volcanic glass, which may or may not contain crystals. It is typically light-colored. Scoria is another vesicula ...

, but it is generally sold as a finer powder and used for a more glossy polish after an initial treatment with coarser pumice powder. Tripoli particles are rounded rather than sharp, making it a milder abrasive. It is usually mixed with oil, sometimes water, and rubbed on the surface of

varnish Varnish is a clear Transparency (optics), transparent hard protective coating or film. It is not to be confused with wood stain. It usually has a yellowish shade due to the manufacturing process and materials used, but it may also be pigmente ...

ed or lacquered wood with a felt pad or cloth. Rotten stone is sometimes used to buff stains out of wood. Some polishing waxes contain powdered rotten stone in a paste substrate. For larger polishing jobs, rotten stone mixed with a binder is applied to polishing wheels. It has also been used to polish

brass Brass is an alloy of copper and zinc, in proportions which can be varied to achieve different colours and mechanical, electrical, acoustic and chemical properties, but copper typically has the larger proportion, generally copper and zinc. I ...

, such as that found on military uniforms, as well as steel and other metals. Plates used in

daguerreotype Daguerreotype was the first publicly available photography, photographic process, widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Louis Daguerre and introduced worldwid ...

s were polished using rotten stone, the finest abrasive available at the time. It is also used to polish jewelry and in toothpastes. Its more common use is as a filler, as used in plastics, paint and rubber.

Sources

Rottenstone has been extensively worked in

South Wales South Wales ( ) is a Regions of Wales, loosely defined region of Wales bordered by England to the east and mid Wales to the north. Generally considered to include the Historic counties of Wales, historic counties of Glamorgan and Monmouthshire ( ...

along the outcrop of the Carboniferous Limestone, particularly within the

Brecon Beacons National Park Brecon Beacons National Park, officially named Bannau Brycheiniog National Park (), is a National parks of the United Kingdom, national park in Wales. It is named after the Brecon Beacons (), the mountain range at its centre. The national park ...

. It occurs at the top of the sequence where the Upper Limestone Shales have been weathered. Innumerable workings were initiated and later abandoned during the course of the nineteenth century, leaving a characteristic terrain of humps and hollows. A notable example is that on the flanks of Cribarth exploited by industrial entrepreneur John Christie.Hughes, S. 1990 ''The Archaeology of an Early Railway System: The Brecon Forest Tramroads'' RCAHMW, Aberystwyth, Dyfed In the United States it is mainly produced in Arkansas, Illinois, and Oklahoma.

References

External links

''On Rotten-Stone and Emery''. Penny Magazine of the Society for the Diffusion of Useful Knowledge. July 15, 1843 Volume 12, p. 270
Abrasives Metalworking Industrial minerals {{Material-stub

Sources

See also

References

External links