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‘The nodules are approximately spherical in shape and have an exterior shell of rhyolite that is more silicified than the host rock.’
‘Bedding planes in the enclosing limestones do not bend around the nodules, and any brachiopods, corals, or other fossils that are in them have been silicified.’
‘The entire fragment is silicified and details of its skeletal structure have been destroyed.’
‘They are largely silicified replacements of the once opaline skeletons, but details of their spicular and skeletal relationships are moderately well preserved.’
‘Bryozoan and trilobite fragments, brachiopod spines, turrilepadid plates, and multiplacophoran spines are silicified.’
‘Silica cells were silicified in the first year, and the frequency was not significantly different among the three leaf ages.’
‘The discovery that silicified trilobites could be dissolved out of limestone in dilute acid added more knowledge more quickly than years of patient preparation from crack-out specimens.’
‘In the high - porosity laminae, individual silicified microbes remain clearly visible and their general morphology and size readily apparent.’
‘In many places, the top of the ‘lower Gasconade’ is marked by a heavy chert zone comprising silicified algae and/or stromatolites.’
‘Morphologically, it is difficult to relate the silicified microbes to the unsilicified or partly silicified microbes.’
‘However, it has been pointed out that the presence of the articulamentum layer is often difficult to detect in the early fossils, since many Paleozoic polyplacophorans are silicified and incompletely preserved.’
‘The limestones, which have been silicified near the granodiorite contact, have in places been intensely metamorphosed into a typical contact-metasomatic assemblage.’
‘Highly silicified stalks to 10 cm in diameter have been found at this locality.’
‘For most large deposits of agate or silicified wood, silica was derived from the decomposition of volcanic rocks.’
‘Cooccurring macrofossils include 18 species of agnostoid and polymeroid trilobites, some of which are partly silicified.’
‘Later, authigenic quartz was precipitated and carbonate phases were partly silicified.’
‘This highly silicified cycad contained bright red-orange to black, diamond-shaped leaf bases of chalcedony up to several centimeters across separated by zones of greenish-yellow chalcedony.’
‘Mite wood borings in the Paleozoic are primarily known from coal ball permineralizations and silicified peat which was deposited in swampy environments.’
‘Where the Zeederbergs-Cheshire contact lacks ironstone horizons, the contact is variably sheared, and adjacent rocks are silicified and characterized by mostly oxidized sulphide impregnation.’
‘Trace amounts of iron oxide impart vibrant red, red-orange, orange, and yellow colors that sometimes contrast markedly with browns and blacks in these silicified trunks.’