Editing Tuff (section)

===Alkaline volcanism===
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 [[claystone]]s, rich in [[kaolin]] with secondary quartz.<ref name=EB1911/> Recent trachyte tuffs are found on the [[Rhine]] (at [[Siebengebirge]]),<ref>{{cite book |last1=Lippolt |first1=H. J. |title=Plateau Uplift |chapter=Distribution of Volcanic Activity in Space and Time |date=1983 |pages=112–120 |doi=10.1007/978-3-642-69219-2_15|isbn=978-3-642-69221-5 }}</ref> in [[Ischia]]<ref>{{cite journal |last1=Gillot |first1=P-Y. |last2=Chiesa |first2=S. |last3=Pasquaré |first3=G. |last4=Vezzoli |first4=L. |title=<33,000-yr K–Ar dating of the volcano–tectonic horst of the Isle of Ischia, Gulf of Naples |journal=Nature |date=September 1982 |volume=299 |issue=5880 |pages=242–245 |doi=10.1038/299242a0|bibcode=1982Natur.299..242G |s2cid=4332634 }}</ref> and near [[Naples]].<ref>{{cite journal |last1=Giannetti |first1=Bernardino |last2=De Casa |first2=Giancarlo |title=Stratigraphy, chronology, and sedimentology of ignimbrites from the white trachytic tuff, Roccamonfina Volcano, Italy |journal=Journal of Volcanology and Geothermal Research |date=March 2000 |volume=96 |issue=3–4 |pages=243–295 |doi=10.1016/S0377-0273(99)00144-4|bibcode=2000JVGR...96..243G }}</ref> Trachyte-carbonatite tuffs have been identified in the [[East African Rift]].<ref>{{cite journal |last1=Macdonald |first1=R. |last2=Kjarsgaard |first2=B. A. |last3=Skilling |first3=I. P. |last4=Davies |first4=G. R. |last5=Hamilton |first5=D. L. |last6=Black |first6=S. |title=Liquid immiscibility between trachyte and carbonate in ash flow tuffs from Kenya |journal=Contributions to Mineralogy and Petrology |date=June 1993 |volume=114 |issue=2 |pages=276–287 |doi=10.1007/BF00307762|bibcode=1993CoMP..114..276M |s2cid=128821707 }}</ref> Alkaline crystal tuffs have been reported from [[Rio de Janeiro (state)|Rio de Janeiro]].<ref>{{cite journal |last1=Motoki |first1=Akihisa |last2=Geraldes |first2=Mauro Cesar |last3=Iwanuch |first3=Woldemar |last4=Vargas |first4=Thais |last5=Motoki |first5=Kenji Freire |last6=Balmant |first6=Alex |last7=Ramos |first7=Marina Nascimento |title=The pyroclastic dyke and welded crystal tuff of the Morro dos Gatos alkaline intrusive complex, State of Rio de Janeiro, Brazil |journal=Rem: Revista Escola de Minas |date=March 2012 |volume=65 |issue=1 |pages=35–45 |doi=10.1590/S0370-44672012000100006|doi-access=free }}</ref>