Volcanic Tuff


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Tuff, Volcanic

 

a dense volcanic rock formed by the cementation of ash, scoria, lapilli, and other éjecta from an erupting volcano. Tuffs consist of fragments of volcanic glass, pumice, and other substances; tuffs composed of whole crystals or crystal fragments are also encountered.

Tuffs are classified according to composition, nature, and fragment sizes. In terms of composition, we distinguish among rhyo-litic, dacitic, andesitic, basaltic, and other tuffs. The color of tuffs varies; Artik tuff is violet-pink, and Ani tuff is orange or yellow (both types are found in the Armenian SSR). Tuffs are formed either by direct deposition from the air during a volcanic eruption or as a result of the transport of tuffaceous material by water or wind.

Tuff is a valuable building material of excellent ornamental quality. It is used, for example, as a filler in light concrete or as a wall material. In the USSR the main tuff deposits are in Armenia. In other countries the most important deposits are near Rome and Naples in Italy and in Iceland.

V. P. PETROV

tuff, volcanic tuff

A low-density, high-porosity rock; composed of volcanic particles, ranging from ash size to small pebble size, which are compacted or cemented together; sometimes used as building stone or as a thermal insulation material.
References in periodicals archive ?
breakage, volcanic tuff and quartz sand are the effective components for the production of composite gypsum binders.
Volcanic tuffs have three different groups as follows: Gulludag Tuff, Melendiz Tuff and Alacasar Tuff.
2011) are the group of volcanic tuffs (Tierra Blanca 4 (TB4), Gl, Tierra Blanca 3 (TB3), Tierra Blanca (TB2), G2, IB, Plan de la Laguna (PL), Tierra Blanca Joven (TBJ) including Arce and Congo) which are placed above the bed rock (Figure 10 and 11).
Religious Residential Meae Mahia Paepae avaia hiamoe Cultural traits Stone tiki (full figure or head only) 0 N N Stone uprights (vesicular basalt) R R/0 N Stone uprights (columnar basalt) R R/0 N Backrest stones R N N Quarried slabs of volcanic tuff O/F 0 O/F (ke'etu) Tiki image carved in bas-relief on R N R ke'etu Veranda pit (pakeho) 0 N?
Eight holes on Target #1 revealed a subcropping, mineralized, volcanic tuff bed.
thick dipping at a 25 to 35 degree angle in an altered silicified volcanic tuff.
The terrigenous rocks usually alternate with acidic volcanic tuffs in the upper parts of the terrigenous group, where their main component is the volcanic glass.
The strongest mineralization occurs in volcanic tuffs and breccias along a distinctive ring fracture zone, about 1 km wide with a 4-5-km dia.
The orebody is hosted in strongly layered volcanic tuffs and rhyolites which occur beneath the gravels.
Unlike the Fish Lake Valley prospect it is a more traditional bulk mining target which covers an area of clay altered Caetano, and Fish Creek formation Tertiary volcanic tuffs.
The soil is volcanic - 5 to 60 % fractured basalt shale and volcanic tuffs.