Tuff (8-14 mm)

Neapolitan yellow tuff (8-14 mm) is a pyroclastic rock characterized by a predominance of ash of various grain sizes, with inclusions of pumice and lava fragments, resulting from explosive-type eruptions of different volcanic centers. Moreover, since it consists mainly of oxides of Aluminum, Potassium, Calcium and Magnesium, it does not undergo chemical processes of oxidation or hydration.

Average chemical analysis:
-SiO2: 60.0%
-Al2O3: 16.0%
-K2O: 3.0%
-Fe2O3 – FeO: 5.0%
-CaO: 2.0%
-Na2O: 3.0%
-MgO: 1.0%
-H2O: 10.0%

Mineralogical composition:
Its main minerals are phillipsite and chabazite for zeolites; smecite and illite for clays; while the few phenocrysts present are alkali feldspars, salitic clinopyroxenes or diopsides, biotite and plagioclase.

Additional info:
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