Tuff is a type of rock made of volcanic ash ejected from a vent during a volcanic eruption. Following ejection and deposition, the ash is lithified into a solid rock. Rock that contains greater than 75% ash is considered tuff, while rock containing 25% to 75% ash is described as tuffaceous.
Tuff is a relatively soft rock, so it has been used for construction since ancient times. Because it is common in Italy, the Romans used it often for construction. The Rapa Nui people used it to make most of the moai statues in Easter Island.
The material that is expelled in a volcanic eruption can be classified into three types:
- Volcanic gases, a mixture made mostly of steam, carbon dioxide, and a sulfur compound (either sulfur dioxide, SO2, or hydrogen sulfide, H2S, depending on the temperature)
- Lava, the name of magma when it emerges and flows over the surface
- Tephra, particles of solid material of all shapes and sizes ejected and thrown through the air
Tephra is made when magma inside the volcano is blown apart by the rapid expansion of hot volcanic gases. Magma commonly explodes as the gas dissolved in it comes out of solution as the pressure decreases when it flows to the surface. These violent explosions produce particles of material that can then fly from the volcano. Solid particles smaller than 2 mm in diameter (sand-sized or smaller) are called volcanic ash.
Volcanic ash is further divided into fine ash, with particle sizes smaller than 0.0625 mm in diameter, and coarse ash, with particle sizes between 0.0625 mm and 2 mm in diameter. Tuff is correspondingly divided into coarse tuff (coarse ash tuff) and fine tuff (fine ash tuff or dust tuff). Consolidated tephra composed mostly of coarser particles is called lapillistone (particles 2 mm to 64 mm in diameter) or agglomerate or pyroclastic breccia (particles over 64 mm in diameter) rather than tuff.
Volcanic ash can vary greatly in composition, and so tuffs are further classified by the composition of the ash from which they formed. Ash from high-silica volcanism, particularly in ash flows, consists mainly of shards of volcanic glass, and tuff formed predominantly from glass shards is described as vitric tuff. The glass shards are typically either irregular in shape or are roughly triangular with convex sides. They are the shattered walls of countless small bubbles that formed in the magma as dissolved gases rapidly came out of solution.
Tuffs formed from ash consisting predominantly of individual crystals are described as crystal tuffs, while those formed from ash consisting predominantly of pulverized rock fragments are described as lithic tuffs.
The chemical composition of volcanic ash reflects the entire range of volcanic rock chemistry, from high-silica rhyolitic ash to low-silica basaltic ash, and tuffs are likewise described as rhyolitic, andesitic, basaltic, and so on.
Transport and lithification
The most straightforward way for volcanic ash to move away from the vent is as ash clouds that are part of an eruption column. These fall to the surface as fallout deposits that are characteristically well-sorted and tend to form a blanket of uniform thickness across terrain. Column collapse results in a more spectacular and destructive form of transport, which takes the form of pyroclastic flows and surges that characteristically are poorly sorted and pool in low terrain. Surge deposits sometimes show sedimentary structures typical of high-velocity flow, such as dunes and antidunes. Volcanic ash already deposited on the surface can be transported as mud flows (lahars) when mingled with water from rainfall or through eruption into a body of water or ice.
Particles of volcanic ash that are sufficiently hot will weld together after settling to the surface, producing a welded tuff. Welding requires temperatures in excess of 600 °C (1,100 °F). If the rock contains scattered, pea-sized fragments or fiamme in it, it is called a welded lapilli-tuff. Welded tuffs (and welded lapilli-tuffs) can be of fallout origin, or deposited from ash flows, as in the case of ignimbrites. During welding, the glass shards and pumice fragments adhere together (necking at point contacts), deform, and compact together, resulting in a eutaxitic fabric. Welded tuff is commonly rhyolitic in composition, but examples of all compositions are known.
A sequence of ash flows may consist of multiple cooling units. These can be distinguished by the degree of welding. The base of a cooling unit is typically unwelded due to chilling from the underlying cold surface, and the degree of welding and of secondary reactions from fluids in the flow increases upwards towards the center of the flow. Welding decreases towards the top of the cooling unit, where the unit cools more rapidly. The intensity of welding may also decrease towards areas in which the deposit is thinner, and with distance from source.
Cooler pyroclastic flows are unwelded and the ash sheets deposited by them are relatively unconsolidated. However, cooled volcanic ash can quickly become lithified because it usually has a high content of volcanic glass. This is a thermodynamically unstable material that reacts rapidly with ground water or sea water, which leaches alkali metals and calcium from the glass. New minerals, such as zeolites, clays, and calcite, crystallize from the dissolved substances and cement the tuff.
Tuffs are further classified by their depositional environment, such as lacustrine tuff, subaerial tuff, or submarine tuff, or by the mechanism by which the ash was transported, such as fallout tuff or ash flow tuff. Reworked tuffs, formed by erosion and redeposition of ash deposits, are usually described by the transport agent, such as aeolian tuff or fluvial tuff.
Tuffs have the potential to be deposited wherever explosive volcanism takes place, and so have a wide distribution in location and age.
Rhyolite tuffs contain pumiceous, glassy fragments and small scoriae with quartz, alkali feldspar, biotite, etc. Iceland, Lipari, Hungary, the Basin and Range of the American southwest, and New Zealand are among the areas where such tuffs are prominent. In the ancient rocks of Wales, Charnwood, etc., similar tuffs are known, but in all cases, they are greatly changed by silicification (which has filled them with opal, chalcedony, and quartz) and by devitrification. The frequent presence of rounded corroded quartz crystals, such as occur in rhyolitic lavas, helps to demonstrate their real nature.
Welded ignimbrites can be highly voluminous, such as the Lava Creek Tuff erupted from Yellowstone Caldera in Wyoming 631,000 years ago. This tuff had an original volume of at least 1,000 cubic kilometers (240 cu mi). Lava Creek tuff is known to be at least 1000 times as large as the deposits of the May 18, 1980 eruption of Mount St. Helens, and it had a Volcanic Explosivity Index (VEI) of 8, greater than any eruption known in the last 10,000 years. Ash flow tuffs cover 7,000 square kilometers (2,700 sq mi) of the North Island of New Zealand and about 100,000 square kilometers (39,000 sq mi) of Nevada. Ash flow tuffs are the only volcanic product with volumes rivaling those of flood basalts.
The Tioga Bentonite of the northeastern United States varies in composition from crystal tuff to tuffaceous shale. It was deposited as ash carried by wind that fell out over the sea and settled to the bottom. It is Devonian in age and likely came from a vent in central Virginia, where the tuff reaches its maximum thickness of about 40 meters (130 ft).
Trachyte tuffs contain little or no quartz, but much sanidine or anorthoclase and sometimes oligoclase feldspar, with occasional biotite, augite, and hornblende. In weathering, they often change to soft red or yellow claystones, rich in kaolin with secondary quartz. Recent trachyte tuffs are found on the Rhine (at Siebengebirge), in Ischia and near Naples. Trachyte-carbonatite tuffs have been identified in the East African Rift. Alkaline crystal tuffs have been reported from Rio de Janeiro.
Andesitic tuffs are exceedingly common. They occur along the whole chain of the Cordilleras and Andes, in the West Indies, New Zealand, Japan, etc. In the Lake District, North Wales, Lorne, the Pentland Hills, the Cheviots, and many other districts of Great Britain, ancient rocks of exactly similar nature are abundant. In color, they are red or brown; their scoriae fragments are of all sizes from huge blocks down to minute granular dust. The cavities are filled with many secondary minerals, such as calcite, chlorite, quartz, epidote, or chalcedony; in microscopic sections, though, the nature of the original lava can nearly always be made out from the shapes and properties of the little crystals which occur in the decomposed glassy base. Even in the smallest details, these ancient tuffs have a complete resemblance to the modern ash beds of Cotopaxi, Krakatoa, and Mont Pelé.
Mafic volcanism typically takes the form of Hawaiian eruptions that are nonexplosive and produce little ash. However, interaction between basaltic magma and groundwater or sea water results in hydromagmatic explosions that produce abundant ash. These deposit ash cones that subsequently can become cemented into tuff cones. Diamond Head, Hawaii, is an example of a tuff cone, as is the island of Ka'ula. The glassy basaltic ash produced in such eruptions rapidly alters to palagonite as part of the process of lithification.
Although conventional mafic volcanism produce little ash, such ash as is formed may accumulate locally as significant deposits. An example is the Pahala ash of Hawaii island, which locally is as thick as 15 meters (49 ft). These deposits also rapidly alter to palagonite, and eventually weather to laterite.
Basaltic tuffs are also found in Skye, Mull, Antrim, and other places, where Paleogene volcanic rocks are found; in Scotland, Derbyshire, and Ireland among the Carboniferous strata, and among the still older rocks of the Lake District, the southern uplands of Scotland, and Wales. They are black, dark green, or red in colour; vary greatly in coarseness, some being full of round spongy bombs a foot or more in diameter; and being often submarine, may contain shale, sandstone, grit, and other sedimentary material, and are occasionally fossiliferous. 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.
Occurrences of ultramafic tuff include surface deposits of kimberlite at maars in the diamond-fields of southern Africa and other regions. The principal variety of kimberlite is a dark bluish-green, serpentine-rich breccia (blue-ground) which, when thoroughly oxidized and weathered, becomes a friable brown or yellow mass (the "yellow-ground"). These breccias were emplaced as gas–solid mixtures and are typically preserved and mined in diatremes that form intrusive pipe-like structures. At depth, some kimberlite breccias grade into root zones of dikes made of unfragmented rock. At the surface, ultramafic tuffs may occur in maar deposits. Because kimberlites are the most common igneous source of diamonds, the transitions from maar to diatreme to root-zone dikes have been studied in detail. Diatreme-facies kimberlite is more properly called an ultramafic breccia rather than a tuff.
Folding and metamorphism
In course of time, changes other than weathering may overtake tuff deposits. Sometimes, they are involved in folding and become sheared and cleaved. Many of the green slates of the English Lake District are finely cleaved ashes. In Charnwood Forest also, the tuffs are slaty and cleaved. The green color is due to the large development of chlorite. Among the crystalline schists of many regions, green beds or green schists occur, which consist of quartz, hornblende, chlorite or biotite, iron oxides, feldspar, etc., and are probably recrystallized or metamorphosed tuffs. They often accompany masses of epidiorite and hornblende – schists which are the corresponding lavas and sills. Some chlorite-schists also are probably altered beds of volcanic tuff. The "Schalsteins" of Devon and Germany include many cleaved and partly recrystallized ash-beds, some of which still retain their fragmental structure, though their lapilli are flattened and drawn out. Their steam cavities are usually filled with calcite, but sometimes with quartz. The more completely altered forms of these rocks are platy, green chloritic schists; in these, however, structures indicating their original volcanic nature only sparingly occur. These are intermediate stages between cleaved tuffs and crystalline schists.
The primary economic value of tuff is as a building material. In the ancient world, tuff's relative softness meant that it was commonly used for construction where it was available. Tuff is common in Italy, and the Romans used it for many buildings and bridges. For example, the whole port of the island of Ventotene (still in use), was carved from tuff. The Servian Wall, built to defend the city of Rome in the fourth century BC, is also built almost entirely from tuff. The Romans also cut tuff into small, rectangular stones that they used to create walls in a pattern known as opus reticulatum.
The peperino, much used at Rome and Naples as a building stone, is a trachyte tuff. Pozzolana also is a decomposed tuff, but of basic character, originally obtained near Naples and used as a cement, but this name is now applied to a number of substances not always of identical character. In the Eifel region of Germany, a trachytic, pumiceous tuff called trass has been extensively worked as a hydraulic mortar.
Tuff of the Eifel region of Germany has been widely used for construction of railroad stations and other buildings in Frankfurt, Hamburg, and other large cities. Construction using the Rochlitz Porphyr, can be seen in the Mannerist-style sculpted portal outside the chapel entrance in Colditz Castle. The trade name Rochlitz Porphyr is the traditional designation for a dimension stone of Saxony with an architectural history over 1,000 years in Germany. The quarries are located near Rochlitz.
Yucca Mountain nuclear waste repository, a U.S. Department of Energy terminal storage facility for spent nuclear reactor and other radioactive waste, is in tuff and ignimbrite in the Basin and Range Province in Nevada. In Napa Valley and Sonoma Valley, California, areas made of tuff are routinely excavated for storage of wine barrels.
Tuff is used extensively in Armenia and Armenian architecture. It is the dominant type of stone used in construction in Armenia's capital Yerevan, Gyumri, Armenia's second largest city, and Ani, the country's medieval capital, now in Turkey. A small village in Armenia was renamed Tufashen (literally "built of tuff") in 1946.
Tuffs are deposited geologically instantaneously and often over a large region. This makes them highly useful as time-stratigraphic markers. The use of tuffs and other tephra deposits in this manner is known as tephrochronology and is particularly useful for Quaternary chronostratigraphy. Individual tuff beds can be "fingerprinted" by their chemical composition and phenocryst assemblages. Absolute ages for tuff beds can be determined by K-Ar, Ar-Ar, or carbon-14 dating. Zircon grains found in many tuffs are highly durable and can survive even metamorphism of the host tuff to schist, allowing absolute ages to be assigned to ancient metamorphic rocks. For example, dating of zircons in a metamorphosed tuff bed in the Pilar Formation provided some of the first evidence for the Picuris orogeny.
- Bentonite – A smectite clay consisting mostly of montmorillonite
- Sillar – A variety of rhyolite containing fragments of andesite
- Eutaxitic texture – Layered or banded texture in some extrusive rock bodies
- Tuffite – Tuff containing both pyroclastic and detrital materials
- Brisbane tuff
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- Fisher, Richard V.; Schmincke, H.-U. (1984). Pyroclastic rocks. Berlin: Springer-Verlag. pp. 89–90. ISBN 3540127569.
- Schmincke, Hans-Ulrich (2003). Volcanism. Berlin: Springer. p. 138. ISBN 9783540436508.
- Schmidt, R. (1981). "Descriptive nomenclature and classification of pyroclastic deposits and fragments: recommendations of the IUGS Subcommission on the Systematics of Igneous Rocks". Geology. 9: 41–43. doi:10.1007/BF01822152. S2CID 128375559. Retrieved 27 September 2020.
- Marcari, G., G. Fabbrocino, and G. Manfredi. "Shear seismic capacity of tuff masonry panels in heritage constructions." Structural Studies, Repairs and Maintenance of Heritage Architecture X 95 (2007): 73.
- Dolan, S.G.; Cates, K.M.; Conrad, C.N.; Copeland, S.R. (14 March 2019). "Home Away from Home: Ancestral Pueblo Fieldhouses in the Northern Rio Grande". Lanl-Ur. 19–21132: 96. Retrieved 29 September 2020.
- Jackson, M. D.; Marra, F.; Hay, R. L.; Cawood, C.; Winkler, E. M. (2005). "The Judicious Selection and Preservation of Tuff and Travertine Building Stone in Ancient Rome*". Archaeometry. 47 (3): 485–510. doi:10.1111/j.1475-4754.2005.00215.x.
- Richards, Colin. 2016. "Making Moai: Reconsidering Concepts of Risk in the Construction of Megalithic Architecture in Rapa Nui (Easter Island)". Rapa Nui–Easter Island: Cultural and Historical Perspectives, pp.150-151
- One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Tuff". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- Fisher and Schmincke 1984, p.96
- Blatt, Harvey (1996). Petrology : igneous, sedimentary, and metamorphic (2nd ed.). New York: W.H. Freeman. pp. 27–29. ISBN 0716724383.
- O'Brien, R. T. (1 March 1963). "Classification of tuffs". Journal of Sedimentary Research. 33 (1): 234–235. Bibcode:1963JSedR..33..234O. doi:10.1306/74D70E20-2B21-11D7-8648000102C1865D.
- Fisher and Schmincke 1984, pp. 98-99
- Philpotts, Anthony R.; Ague, Jay J. (2009). Principles of igneous and metamorphic petrology (2nd ed.). Cambridge, UK: Cambridge University Press. p. 73. ISBN 9780521880060.
- Schmincke 2003, pp.138, 157
- Fisher and Schmincke 1984, p.215
- Schmincke 2003, pp.186-187
- Fisher and Schmincke 1984, p.209
- Blatt and Tracy 1996, p.29
- Ross, Clarence S.; Smith, Robert L. (1961). "Ash-flow tuffs: Their origin, geologic relations, and identification". USGS Profession Paper Series. Professional Paper (366): 19. doi:10.3133/pp366.
- Philpotts and Ague 2009, p.73
- Jónasson, K. (December 1994). "Rhyolite volcanism in the Krafla central volcano, north-east Iceland". Bulletin of Volcanology. 56 (6–7): 516–528. Bibcode:1994BVol...56..516J. doi:10.1007/BF00302832. S2CID 129012636.
- Crisci, G. M.; Rosa, R.; Lanzafame, G.; Mazzuoli, R.; Sheridan, M. F.; Zuffa, G. G. (September 1981). "Monte guardia sequence: a late-pleistocene eruptive cycle on Lipari (Italy)". Bulletin Volcanologique. 44 (3): 241–255. Bibcode:1981BVol...44..241C. doi:10.1007/BF02600562. S2CID 128627430.
- Zelenka, Tibor; Balázs, Endre; Balogh, Kadosa; Kiss, János (December 2004). "Buried Neogene volcanic structures in Hungary" (PDF). Acta Geologica Hungarica. 47 (2–3): 177–219. doi:10.1556/ageol.47.2004.2-3.6.
- Howells, M. F.; Reedman, A. J.; Campbell, S. D. G. (May 1986). "The submarine eruption and emplacement of the Lower Rhyolitic Tuff Formation (Ordovician), N Wales". Journal of the Geological Society. 143 (3): 411–423. Bibcode:1986JGSoc.143..411H. doi:10.1144/gsjgs.143.3.0411. S2CID 129147300.
- Carney, John (2000). "Igneous processes within late Precambrian volcanic centres near Whitwick, northwestern Charnwood Forest" (PDF). Mercian Geologist. 15 (1): 7–28. Retrieved 1 October 2020.
- McArthur, A. N.; Cas, R. A. F.; Orton, G. J. (30 November 1998). "Distribution and significance of crystalline, perlitic and vesicular textures in the Ordovician Garth Tuff (Wales)". Bulletin of Volcanology. 60 (4): 260–285. Bibcode:1998BVol...60..260M. doi:10.1007/s004450050232. S2CID 128474768.
- Matthews, Naomi E.; Vazquez, Jorge A.; Calvert, Andrew T. (August 2015). "Age of the Lava Creek supereruption and magma chamber assembly at Yellowstone based on 40 Ar/ 39 Ar and U-Pb dating of sanidine and zircon crystals: AGE OF THE LAVA CREEK SUPERERUPTION". Geochemistry, Geophysics, Geosystems. 16 (8): 2508–2528. doi:10.1002/2015GC005881.
- "What is a supervolcano? What is a supereruption?". Natural Hazards. United States Geological Survey. Retrieved 30 September 2020.
- Dennison, J. M.; Textoris, D. A. (March 1970). "Devonian tioga tuff in Northeastern United States". Bulletin Volcanologique. 34 (1): 289–294. Bibcode:1970BVol...34..289D. doi:10.1007/BF02597791. S2CID 129708915.
- Lippolt, H. J. (1983). "Distribution of Volcanic Activity in Space and Time". Plateau Uplift: 112–120. doi:10.1007/978-3-642-69219-2_15. ISBN 978-3-642-69221-5.
- Gillot, P-Y.; Chiesa, S.; Pasquaré, G.; Vezzoli, L. (September 1982). "<33,000-yr K–Ar dating of the volcano–tectonic horst of the Isle of Ischia, Gulf of Naples". Nature. 299 (5880): 242–245. Bibcode:1982Natur.299..242G. doi:10.1038/299242a0. S2CID 4332634.
- Giannetti, Bernardino; De Casa, Giancarlo (March 2000). "Stratigraphy, chronology, and sedimentology of ignimbrites from the white trachytic tuff, Roccamonfina Volcano, Italy". Journal of Volcanology and Geothermal Research. 96 (3–4): 243–295. Bibcode:2000JVGR...96..243G. doi:10.1016/S0377-0273(99)00144-4.
- Macdonald, R.; Kjarsgaard, B. A.; Skilling, I. P.; Davies, G. R.; Hamilton, D. L.; Black, S. (June 1993). "Liquid immiscibility between trachyte and carbonate in ash flow tuffs from Kenya". Contributions to Mineralogy and Petrology. 114 (2): 276–287. Bibcode:1993CoMP..114..276M. doi:10.1007/BF00307762. S2CID 128821707.
- Motoki, Akihisa; Geraldes, Mauro Cesar; Iwanuch, Woldemar; Vargas, Thais; Motoki, Kenji Freire; Balmant, Alex; Ramos, Marina Nascimento (March 2012). "The pyroclastic dyke and welded crystal tuff of the Morro dos Gatos alkaline intrusive complex, State of Rio de Janeiro, Brazil". Rem: Revista Escola de Minas. 65 (1): 35���45. doi:10.1590/S0370-44672012000100006.
- Donnelly-Nolan, Julie M.; Nolan, K. Michael (1 October 1986). "Catastrophic flooding and eruption of ash-flow tuff at Medicine Lake volcano, California". Geology. 14 (10): 875–878. Bibcode:1986Geo....14..875D. doi:10.1130/0091-7613(1986)14<875:CFAEOA>2.0.CO;2.
- Nokleberg, Warren J.; Jones, David L.; Silberling, Norman J. (1 October 1985). "Origin and tectonic evolution of the Maclaren and Wrangellia terranes, eastern Alaska Range, Alaska". GSA Bulletin. 96 (10): 1251–1270. Bibcode:1985GSAB...96.1251N. doi:10.1130/0016-7606(1985)96<1251:OATEOT>2.0.CO;2.
- Grunder, Anita L. (1987). "Low ?18O silicic volcanic rocks at the Calabozos caldera complex, southern Andes: Evidence for upper-crustal contamination". Contributions to Mineralogy and Petrology. 95 (1): 71–81. doi:10.1007/BF00518031. S2CID 128952431.
- Cronin, Shane J.; Neall, Vincent E.; Palmer, Alan S. (January 1996). "Geological history of the north-eastern ring plain of Ruapehu volcano, New Zealand". Quaternary International. 34–36: 21–28. Bibcode:1996QuInt..34...21C. doi:10.1016/1040-6182(95)00066-6.
- Tatsumi, Yoshiyuki; Ishizaka, Kyoichi (April 1982). "Magnesian andesite and basalt from Shodo-Shima Island, southwest Japan, and their bearing on the genesis of calc-alkaline andesites". Lithos. 15 (2): 161–172. Bibcode:1982Litho..15..161T. doi:10.1016/0024-4937(82)90007-X.
- Oertel, G. (1970). "Deformation of a Slaty, Lapillar Tuff in the Lake District, England". Geological Society of America Bulletin. 81 (4): 1173. Bibcode:1970GSAB...81.1173O. doi:10.1130/0016-7606(1970)81[1173:DOASLT]2.0.CO;2.
- Macdonald, Gordon A. (1983). Volcanoes in the sea : the geology of Hawaii (2nd ed.). Honolulu: University of Hawaii Press. p. 9. ISBN 0824808320.
- Macdonald 1983, pp.17-20
- Macdonald 1983, pp.349-353
- Richan, Lindsay; Gibson, Harold L.; Houlé, Michel G.; Lesher, C. Michael (2015). "Mode of emplacement of Archean komatiitic tuffs and flows in the Selkirk Bay area, Melville Peninsula, Nunavut, Canada". Precambrian Research. 263: 174–196. Bibcode:2015PreR..263..174R. doi:10.1016/j.precamres.2015.03.004.
- Huber, M.S.; Byerly, G.R. (2018). "Volcanological and petrogenetic characteristics of komatiites of the 3.3 Ga Saw Mill Complex, Weltevreden Formation, Barberton Greenstone Belt, South Africa". South African Journal of Geology. 121 (4): 463–486. doi:10.25131/sajg.121.0031.
- Panei, Liliana (10 April 2010). "The tuffs of the "Servian Wall" in Rome: Materials from the local quarries and from the conquered territories". ArchéoSciences (34): 39–43. doi:10.4000/archeosciences.2599.
- Giavarini, Carlo, A. Samueli Ferretti, and Maria Laura Santarelli. 2006. "Mechanical characteristics of Roman ‘opus caementicium’". Fracture and Failure of Natural Building Stones. Applications in the Restoration of Ancient Monuments. pp.108, 110
- Schmincke 2003, pp.280-281
- Georg Dehio: Handbuch der deutschen Kunstdenkmäler, Sachsen II. Deutscher Kunstverlag, München, Berlin 1998, p. 160
- Heiner Siedel: Sächsische „Porphyrtuffe“ aus dem Rotliegend als Baugesteine: Vorkommen und Abbau, Anwendung, Eigenschaften und Verwitterung. In: Institut für Steinkonservierung e. V. Bericht Nr. 22, 2006, p. 47-58. "Archived copy" (PDF). Archived from the original (PDF) on 2011-06-11. Retrieved 2010-05-09.CS1 maint: archived copy as title (link)
- Long, Jane C.S.; Ewing, Rodney C. (19 May 2004). "YUCCA MOUNTAIN: Earth-Science Issues at a Geologic Repository for High-Level Nuclear Waste". Annual Review of Earth and Planetary Sciences. 32 (1): 363–401. Bibcode:2004AREPS..32..363L. doi:10.1146/annurev.earth.32.092203.122444.
- Kositsky, Andrew; Lewis, Scott (2016). "Seismic Performance of Wine Caves" (PDF). The World Tunnel Conference. Retrieved 1 October 2020.
- Holding, N. (2006). Armenia: with Nagorno Karabagh. Bradt Travel Guides. p. 32. ISBN 978-1-84162-163-0. Retrieved May 26, 2010.
- Billock, Jennifer (28 December 2016). "How Ancient Volcanoes Created Armenia's Pink City". Smithsonian. Archived from the original on 9 June 2020.
...pink tuff is rare outside of the region and Yerevan is the only major city built out of this stone.
- Lottman, Herbert R. "Despite Ages of Captivity, The Armenians Persevere". The New York Times.
The city, whose population is now upwards of 800,000, has been rebuilt in the rosy volcanic stone called tufa...
- Haviland, William A; Harald, E. L. Prins; Dana, Walrath; McBride, Bunny (2015). The Essence of Anthropology (4th ed.). Cengage Learning. p. 137.
...walls of monumental buildings at Ani (including the fortifications) were built of smoothly dressed blocks of tuff stone...
- Hakobian, T. Kh.; Melik-Bakhshian, St. T.; Barseghian, H. Kh. (2001). "Տուֆաշեն [Tufashen]". Հայաստանի և հարակից շրջանների տեղանունների բառարան [Dictionary of Toponyms of Armenia and Surrounding Regions] Volume V (in Armenian). Yerevan University Press. p. 147.
- Philpotts and Ague 2009, p.74
- Fisher and Schminke 1984, pp.352-356
- Daniel, Christopher G.; Pfeifer, Lily S.; Jones, James V, III; McFarlane, Christopher M. (2013). "Detrital zircon evidence for non-Laurentian provenance, Mesoproterozoic (ca. 1490–1450 Ma) deposition and orogenesis in a reconstructed orogenic belt, northern New Mexico, USA: Defining the Picuris orogeny". GSA Bulletin. 125 (9–10): 1423–1441. Bibcode:2013GSAB..125.1423D. doi:10.1130/B30804.1. Retrieved 17 April 2020.
- "Definition of 'tuff'". Collins English Dictionary. HarperCollins. Retrieved 30 September 2020.