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(volcanic) tuff

(volcanic) tuff

SRI Petrography ID: 35

Ettringer
Deutschland

tuff

Kieslinger Dekorgestein und Baugesteinsammlung
GBA-ID.-No.:137 , drawer-No:19

Names

[de] (vulkanischer) Tuff
[en] (volcanic) tuff

Description

volcanic tuff is a pyroclastic, consolidated rock composed of compacted and cemented volcanic ash, from volcanic eruptions. The rock is often soft and porous.
Texture and chemical / mineralogical composition are variable, the grain size of the ash is below 4 mm (above 4 mm: volcanic breccia).
Different types of tuffs: Welded tuff, rhyolite tuff, trachyte tuff, andesitic tuff, basaltic tuff, ultramafic tuff, ...)

Color

variable (depending on weathering and chemical composition), mostly greyish, brown, yellow e.g. “Yellow tuff of Naples”

Grain Size

fine grained, sometimes glassy, fragments below 4 mm

Texture

variable

Minerals

variable, depending on the type of tuff

Occurences

World wide wherever volcanic areas, Italy, Easter Islands, Eiffel (Germany)

Comments

Volcanic tuff was widely used for construction purposes (e.g. Servian Wall in Rome, 4th century BC)

Classification

Class

IGNEOUS ROCKS

Broader Terms

pyroclastic rocks

Narrower Terms

Germany-tuff

Greece-tuff

Hungary-tuff

Mexico-tuff