(n.) An impure, massive, flintlike quartz or hornstone, of a dull color.
Example Sentences:
(1) Occurrence of well-preserved rod-shaped and coccoid bacteria in the Precambrian Gunflint chert (1.9 x 10(9) years old) has been demonstrated by electron microscopy.
(2) In order to evaluate the degree of morphological preservation of erythrocytes in bloodstains, an accidental human blood smear on white chert and several experimental bloodstains on hard substrates (the same stone-white chert; another type of stone-graywacke; a non-stone support-stainless steel), were stored in a room, in non-sterile and fluctuating conditions, for lengths of time ranging from 3 to 18 months.
(3) Large amounts of well preserved microfossils have been reported from the cherts of the Upper Proterozoic of the Bohemian Massif (Middle Europe).
(4) Two billion year old black chert lenses from the Duck Creek formation, northwestern Western Australia, contain abundant organically preserved microorganisms which are morphologically similar to fossils of approximately the same age from the Gunflint formation, Ontario.
Conchoidal
Definition:
(a.) Having elevations or depressions in form like one half of a bivalve shell; -- applied principally to a surface produced by fracture.
Example Sentences:
(1) Those differences can be summarized as follows: (1) the occurrence of pronounced, highly curved hackle marks, which could in many instances be mistaken for conchoidal marks;(2)the appearance of the beveled edges bordering the cratering on the side opposite origin of force; and (3) a more apparent tendency toward an inverse relationship of muzzle velocity and energy to radial fracture length and degree of curving along crater boundaries.
(2) These figures were assumed to be the very early stage of formation of conchoidal bodies at the LM level, so-called Schaumann bodies.
(3) Their similitude with other reported intracellular calcareous bodies occurring in malakoplakia, infectious orchitis (Michaelis-Guttman' bodies or calcosphaerites), in beryllium granulomas (conchoid bodies) and sarcoidosis (Schaumann bodies) is discussed.
(4) Sclerotic granulomas with giant cells, conchoidal bodies, iron deposition in the pulmonary stroma--all these lung alterations allowed one to establish a diagnosis of lung berylliosis.
(5) Several patterns of calcification were noted including bubbly, plate-like, elongate, and conchoidal forms.
(6) Lung biopsies in the index cases revealed an interstitial infiltration of inflammatory cells and aggregates of conchoid bodies surrounded by multinucleated giant cells.