Argillaceous brown iron ore is often known in Germany as Thoneisenstein; but the corresponding term in English (clay iron stone) is applied to nodular forms of impure chalybite.
The commonest state of aggregation is that of radially arranged fibres, the external surface of the mass being globular, nodular or stalactitic in form.
The Coal Measures, forming the third great member of the Carboniferous series, consist of alternations of shales and sandstones, with beds of coal and nodular ironstones, which together make up a thickness of many thousands of feet - from 12,000 to 14,000 ft.
Crystals of zeolites (phillipsite) form in the red-clay as radiate, nodular groups.
The Triassic rocks are arranged in two groups, a lower, composed of conglomerates and sandstones, and an upper one consisting of red and mottled shales and marls with thin sandstones and nodular limestones.
It was in the year 1886 that Hellriegel and Wilfarth first published in Germany the results of investigations in which they demonstrated that, through the agency of micro-organisms dwelling in nodular outgrowths on the roots of ordinary leguminous plants, the latter are enabled to assimilate the free nitrogen of the air.
Both these genera have the toe-bones of the irregular nodular form distinctive of modern camels, so that we may safely infer that the feet themselves had assumed the cushiontype.
Even the growth of the well-known nodular incrustations in iron pipes is much reduced by sand filtration.
A series of black shales with nodular limestones, the Pendleside series, rests upon the Mountain Limestone on the east, south and north-west; much of the upper course of the Derwent has been cut through these soft beds.
Thick, with nodular segregations and abundant cavities which are often lined with zeolites.