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 Wales ...

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 accordin ...

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 metalsmithing and in

woodworking Woodworking is the skill of making items from wood, and includes cabinet making (cabinetry and furniture), wood carving, woodworking joints, joinery, carpentry, and woodturning. History Along with Rock (geology), stone, clay and animal parts, ...

. It is usually weathered

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

mixed with

diatom A diatom (Neo-Latin ''diatoma''), "a cutting through, a severance", from el, διάτομος, diátomos, "cut in half, divided equally" from el, διατέμνω, diatémno, "to cut in twain". is any member of a large group comprising sev ...

aceous, amorphous, or crystalline

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

. It has similar applications to

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

, 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 transparent hard protective coating or film. It is not a stain. It usually has a yellowish shade from the manufacturing process and materials used, but it may also be pigmented as desired, and is sold commercially in various ...

ed or lacquered wood with a felt pad or cloth. Rotten stone is sometimes used to buff stains out of wood. Some polishing

wax Waxes are a diverse class of organic compounds that are lipophilic, malleable solids near ambient temperatures. They include higher alkanes and lipids, typically with melting points above about 40 °C (104 °F), melting to giv ...

es 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 (Cu) and zinc (Zn), in proportions which can be varied to achieve different mechanical, electrical, and chemical properties. It is a substitutional alloy: atoms of the two constituents may replace each other with ...

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

daguerreotype Daguerreotype (; french: daguerréotype) was the first publicly available photographic process; it was widely used during the 1840s and 1850s. "Daguerreotype" also refers to an image created through this process. Invented by Louis Daguerre an ...

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 ( cy, De Cymru) is a 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 Glamorgan and Monmouthshire, south Wales extends westwards ...

along the outcrop of the

Carboniferous Limestone Carboniferous Limestone is a collective term for the succession of limestones occurring widely throughout Great Britain and Ireland that were deposited during the Dinantian Epoch of the Carboniferous Period. These rocks formed between 363 and ...

, particularly within the

Brecon Beacons National Park The Brecon Beacons National Park ( cy, Parc Cenedlaethol Bannau Brycheiniog) is one of three national parks in Wales, and is centred on the Brecon Beacons range of hills in southern Wales. It includes the Black Mountain (range), Black Mountain ...

. It occurs at the top of the sequence where the

Upper Limestone Shale Upper may refer to: * Shoe upper or ''vamp'', the part of a shoe on the top of the foot * Stimulant, drugs which induce temporary improvements in either mental or physical function or both * ''Upper'', the original film title for the 2013 found f ...

s 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 Cribarth, sometimes referred to as the Sleeping Giant, is a hill in the Brecon Beacons National Park located in the traditional county of Brecknockshire (currently administered part of the unitary authority of Powys) in southern Wales. The summit ...

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