Tuff (3) Raw Minerals Stones Rocks Collecting

Description

Origin : Italy (Lazio)

Etruscan Tuff of Civita Castellana 41-55 gr - cm 5-6,5 Raw Minerals Stones Rocks for Collection.

The tuff (Latin: tofus or Tophus) is an igneous rock, in particular is the most widespread of pyroclastic rocks.
The tuffs - understood as different varieties of tufa - were made up mostly of lapilli size between 2 mm and 30 mm, emitted during a volcanic eruption. With the name of tuffites indicates general rocks made of volcanic material debris, possibly also associated with sea shells.
The structure of the tuffs is called cinerica vitroclastica or for the appearance of the glass portion that appears finely divided and fragmented.
The lapilli smaller manage to imprison sometimes those of greatest dimension and that the solidification is carried out also through the action of water.
The environment in which these lapilli are deposited can be extremely variable and, together with the composition of the rock, determines the characteristics of color, structure and texture of the tuffs.
The tuffs of Latium are mainly the result of the action of the volcano Sabatino in the period roughly between 600,000 and 300,000 years ago. A second area where they are deposited pyroclastic classify various types of tuff.
The tuff, abundant in volcanic districts of Lazio, began to be used as a building material since the seventh century BC, the Romans prisci, other Latins and Etruscans, because it is a rock rather resistant but light and workable. In Roman times it was also used as the basis for hydraulic mortars. It was used also for more recent buildings such as the city of founding in Pontine.
Although the name "tuff" go strictly reserved for formations of volcanic origin, it is used to indicate different rocks, united by the fact of being light, medium hard and easy to work. Especially in some Italian regions free of deposits tuffaceous volcanic tuff is called the porous limestone (ex .: the tuff of Puglia).