Crystal Tuff

crystal tuff

[¦krist·əl ′təf]
(geology)
Consolidated volcanic ash in which crystals and crystal fragments predominate.

Crystal Tuff

 

a rock, a variety of volcanic tuff consisting almost totally of crystals or their fragments. Crystal tuff is formed during volcanic eruptions, when fragments of lava with crystals formed in the volcanic focus are ejected into the air. The blistered light-weight volcanic glass is carried by the wind far from the site of the eruption; the more dense and heavy crystals fall sooner, forming crystal tuff.

References in periodicals archive ?
The veins occur within red-maroon crystal tuff volcanics which appear to stratigraphically overlie mafic volcanic units.
Geologists have now found some of that age-old rock - known as crystal tuff - from Boon's Quarry, to the north of Nuneaton and a chunk of the volcanic material has been put on display at the Market Hall Museum in Warwick.
Smaller and more restricted bodies of crystal tuff and a quartz-feldspar porphyry are found locally at the base of the pumice tuff and on the south flank of the deposit, respectively.
Soon after, late Arenig felsic volcanism from distant sources deposited several metres of sandy and silty tuff, and minor crystal tuff along with mudstone in some localities, followed by minor local mafic tuff and flows (Lower Birch Island Member of Turnbull Mountain Formation).
The crystal tuff reported in the Grand Pitch Formation of the Shin Pond quadrangle along Seboeis River (Neuman 1967, p.
A few brachiopod fragments were found in the mudchip sandstone within a few metres stratigraphically below crystal tuff (the Headwaters of the Middle Hayden fossil locality, Figs.
There, about 30 m of thick-bedded, medium- to fine-grained, quartz-feldspar-crystal-rich volcaniclastic sandstone, crystal tuff and ash tuff of the member have been interpreted as a sedimentary sequence (Little Falls section; Fyffe et al.
The fossiliferous sandstone appears to be less than a few metres stratigraphically below crystal tuff. Neuman determined that the collection (GSC loc.
The sampled horizon is a massive, dark grey, fine-grained, crystal tuff that is interbedded with coarse, lithic tuff containing mafic and felsic fragments.
Felsic crystal tuff within the Campbell Point Member of the Waweig Formation (sample NB99-9) was collected from an outcrop on the west side of Route 127 (lat.
A belt of Silurian felsic lithic and crystal tuffs, mafic flows and tuffs, and tuffaceous siltstone to the southeast of the Beaver arbour-Belleisle Fault (Fig.