Tuff

welded tufftuffaceoustuffsashstonetufatuff stonevolcanic tuffweldedandesitic tuffashfall deposits
Tuff (from the Italian tufo), also known as volcanic tuff, is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption.wikipedia
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Tufa

tufaceousGeochemistrytufa rock
Tuff is sometimes erroneously called "tufa", particularly when used as construction material, but properly speaking, tufa is a limestone precipitated from groundwater.
Tufa, which is calcareous, should not be confused with tuff, a porous volcanic rock with a similar etymology that is sometimes also called "tufa".

Moai

Easter Island statuesEaster Island Headmoais
The Rapa Nui people used it to make most of the moai statues in Easter Island.
All but 53 of the more than 900 moai known to date were carved from tuff (a compressed volcanic ash) from Rano Raraku, where 394 moai in varying states of completion are still visible today.

Tephra

pyroclastpyroclasticpyroclastic material
Once clasts have fallen to the ground, they remain as tephra unless hot enough to fuse together into pyroclastic rock or tuff.

Volcano

volcanicvolcanoesvolcanic igneous activity
Tuff (from the Italian tufo), also known as volcanic tuff, is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption.

Ignimbrite

ignimbriticignimbrite rockmetaignimbrites
Welded tuffs (and welded lapilli-tuffs) can be of fallout origin, or deposited from pyroclastic density currents, as in the case of ignimbrites.
Ignimbrite is a variety of hardened tuff.

Lava

lava flowlava flowspahoehoe
Cinder cones are formed from tephra or ash and tuff which is thrown from an explosive vent.

Fiamme

fiamme texture
Strictly speaking, if the rock contains scattered, pea-sized fragments or fiamme in it, it is called a welded lapilli-tuff.
They can occur in welded pyroclastic fall deposits and in ignimbrites, which are the deposits of pumiceous pyroclastic density currents.

Palagonite

palagonitizedpalagonite tuffpalagonitic
In St. Vincent and Martinique in 1902, much of the dust was composed of minute crystals enclosed in thin films of glass because the lava at the moment of eruption had very nearly solidified as a crystalline mass. Some basaltic volcanoes, though, have ejected great quantities of black glassy scoria, which, after consolidation, weather to a red soft rock known as palagonite; tuffs of this kind occur in Iceland and Sicily.
The water flashes to steam on contact with the hot lava and the small fragments of lava react with the steam to form the light colored palagonite tuff cones common in areas of basaltic eruptions in contact with water.

Lava Creek Tuff

Lava Creek eruptionash over North America
Welded ignimbrites can be highly voluminous, such as the Lava Creek Tuff erupted from Yellowstone Caldera in Wyoming 640,000 years ago.
The Lava Creek Tuff is a tuff formation in Wyoming, Montana and Idaho, United States, created during the Lava Creek eruption around 630,000 years ago, which formed the Yellowstone Caldera.

Agglomerate

agglomeraticAgglomeriticvolcanic agglomerate
Any ash in which they are very abundant is called an agglomerate.
There are various differences between agglomerates and ordinary ash beds or tuffs.

Igneous rock

igneousigneous rocksdecompression melting
Apart from adventitious material, such as fragments of the older rocks, pieces of trees, etc., the contents of an ash deposit may be described as consisting of more or less crystalline igneous rocks.
Intermediate composition magma, such as andesite, tends to form cinder cones of intermingled ash, tuff and lava, and may have a viscosity similar to thick, cold molasses or even rubber when erupted.

Easter Island

Rapa NuiIsla de PascuaEaster
The Rapa Nui people used it to make most of the moai statues in Easter Island.
Almost all (95%) moai were carved from compressed, easily worked solidified volcanic ash or tuff found at a single site on the side of the extinct volcano Rano Raraku.

Rhyolite

rhyoliticrhyolitesliparite
In the Lipari Islands and Hungary, acid (rhyolitic) tuffs, of pale grey or yellow color, largely composed of lumps and fragments of pumice, occur.
Many eruptions of rhyolite are highly explosive and the deposits may consist of fallout tephra/tuff or of ignimbrites.

Rochlitz

An example of this tuff, Rochlitz Porphyr, can be seen in the Mannerist-style sculpted portal outside the chapel entrance in Colditz Castle.
349 m (NHN)) is of Rotliegend volcanic origin (latest Carboniferous to Guadalupian) and consists to a large extent of so-called Rochlitzer Porphyr, a rhyolitic tuff or ignimbrite.

Ischia

PithekoussaiPithecusaeIschia Island
Recent trachyte tuffs are found on the Rhine (at Siebengebirge), in Ischia, near Naples, Hungary, etc.
The eruption of the trachytic Green Tuff ignimbrite about 56,000 years ago was followed by caldera formation.

Rome

Rome, ItalyRomanRoma
A tuff of recent origin is generally loose and incoherent, but the older tuffs have been, in most cases, cemented together by pressure and the action of infiltrating water, making rocks which, while not very hard, are strong enough to be extensively used for building purposes (e.g. in the neighborhood of Rome). The Servian Wall, built to defend the city of Rome in the fourth century BC, is also built almost entirely from tuff.
Originally they were carved through tuff, a soft volcanic rock, outside the boundaries of the city, because Roman law forbade burial places within city limits.

Lapilli

lapilli-tuffaccretionary lapillicinders
Strictly speaking, if the rock contains scattered, pea-sized fragments or fiamme in it, it is called a welded lapilli-tuff.
Lapilli tuffs are a very common form of volcanic rock typical of rhyolite, andesite and dacite pyroclastic eruptions, where thick layers of lapilli can be deposited during a basal surge eruption.

West Indies

West IndianCaribbean basinWest Indians
Blocks of these crystalline minerals (anorthite, olivine, augite, and hornblende) are common objects in the tuffs of many of the West Indian volcanoes.
They consist of metamorphosed graywacke, argillite, tuff, mafic igneous extrusive flows, and carbonate rock.

Basalt

basalticcolumnar basaltpillow basalt
In St. Vincent and Martinique in 1902, much of the dust was composed of minute crystals enclosed in thin films of glass because the lava at the moment of eruption had very nearly solidified as a crystalline mass. Some basaltic volcanoes, though, have ejected great quantities of black glassy scoria, which, after consolidation, weather to a red soft rock known as palagonite; tuffs of this kind occur in Iceland and Sicily.
Basaltic tuff or pyroclastic rocks are rare but not unknown.

Pyroclastic rock

pyroclasticvolcaniclasticpyroclastics
Welded tuff is a pyroclastic rock, of any origin, that was sufficiently hot at the time of deposition to weld together.
Pyroclastic rocks may be a range of clast sizes, from the largest agglomerates, to very fine ashes and tuffs.

Colditz Castle

ColditzOflag IVc
An example of this tuff, Rochlitz Porphyr, can be seen in the Mannerist-style sculpted portal outside the chapel entrance in Colditz Castle.
During this period the portal at what is known as the church house was created during 1584, made of Rochlitz Porphyr (rhyolite tuff) and richly decorated in the mannerist style by Andreas Walther II.

Naples

Naples, ItalyNapoliNeapolitan
Recent trachyte tuffs are found on the Rhine (at Siebengebirge), in Ischia, near Naples, Hungary, etc.
There are also a number of ancient Greco-Roman reservoirs dug out from the soft tufo stone on which, and from which, much of the city is built.

Zeolite

zeoliteszeoliticdachiardite
Recent basaltic tuffs are found in Iceland, the Faroe Islands, Jan Mayen, Sicily, the Hawaiian Islands, Samoa, etc. When weathered, they are filled with calcite, chlorite, serpentine, and especially where the lavas contain nepheline or leucite, are often rich in zeolites, such as analcite, prehnite, natrolite, scolecite, chabazite, heulandite, etc.
According to the United States Geological Survey, it is likely that a significant percentage of the material sold as zeolites in some countries is ground or sawn volcanic tuff that contains only a small amount of zeolites.

Sill (geology)

sillsillsigneous sill
They often accompany masses of epidiorite and hornblende – schists which are the corresponding lavas and sills.
In geology, a sill is a tabular sheet intrusion that has intruded between older layers of sedimentary rock, beds of volcanic lava or tuff, or along the direction of foliation in metamorphic rock.

Servian Wall

Servian Wallsfirst city wallsportion of surviving wall
The Servian Wall, built to defend the city of Rome in the fourth century BC, is also built almost entirely from tuff.
The wall was built from large blocks of tuff (a volcanic rock made from ash and rock fragments ejected during an eruption) quarried from the Grotta Oscura quarry near Rome's early rival Veii, presumably after its defeat by Rome in the 390s.