In many parts, particularly in the eastern basin, a calcareous or siliceous crust, from half an inch to three inches in thickness, is met with; and Natterer suggested that the formation of this crust may be due to the production of carbonate of ammonium where deposits containing organic matter are undergoing oxidation, and the consequent precipitation of carbonate of lime and other substances from the waters nearer the surface.
Travers has suggested that it may explain the liberation of helium from minerals by heat, the gas being enabled to permeate the siliceous materials in which it is enclosed.
Mineral salts, especially calcium carbonate, often rich in acidic humous compounds, and characterized by oak and birch woods, siliceous pasture, and heaths with much acidic humus in the sandy soil.
The siliceous Claiborne (or Tallahatta Buhrstone) formation lies south-westward from the last-named in a strip 10-30 m.
Wide, whose south-eastern extremity is the intersection of the 32nd meridian with the Alabama boundary, is characterized by beds of aluminous grey and white sandstone, aluminous and siliceous clay-stone, quartzitic sandstone, and green sand and marls.
The Jackson formation south-west of the Lisbon beds, is made up chiefly of grey calcareous clay marls, bluish lignitic clays, green-sand and grey siliceous sands.
About half of the varieties of forest trees in the United States are found, and 1 Almost everywhere limestone is the underlying rock, but siliceous sands, brought out by the Atlantic rivers to the N.E., are carried the whole length of the Florida coast by marine action.
The springs are principally alkaline, alkaline and siliceous, acidic, or acidic and hepatic (sulphurous).
Muscovite and biotite are commonly found in siliceous rocks, whilst phlogopite is characteristic of calcareous rocks.
Aluminium, when pure and kept out of contact with siliceous matter, is only oxidized at a white heat, and then very slowly, into alumina, Al 2 O 3.
It includes chalky limestones, siliceous earths, red clay, and, at the top, a layer of mudstone composed mainly of volcanic dust.
The limestones contain Globigerina and other Foraminifera, the siliceous beds are made of Radiolaria, sponge spicules and diatoms, while the red clay closely resembles the red clay of the deepest parts of the oceans.
These rocks, which include some highly siliceous lavas, form part of the Eocene series that is so conspicuously displayed above Carlingford in Co.
(4) The siliceous sinter at XII.
A particularly fine-grained mud is formed on the low coasts of the eastern border of the North Sea by a mixture of the finest sediment carried down by the slow-running rivers with the calcareous or siliceous remains of plankton.
To this inconceivably slowly-growing deposit of inorganic material over the ocean floor there is added an overwhelmingly more rapid contribution of the remains of calcareous and siliceous planktonic and benthonic organisms, which tend to bury the slower accumulating material under a blanket of globigerina, pteropod, diatom or radiolarian ooze.
It is a remarkable geographical fact that on the rises and in the basins of moderate depth of the open ocean the organic oozes preponderate, but in the abysmal depressions below 2500 or 3000 fathoms, whether these lie in the middle or near the edges of the great ocean spaces, there is found only the red clay, with a minimum of calcium carbonate, though sometimes with a considerable admixture of the siliceous remains of radiolarians.
It has been found sporadically near the Aleutian Islands, between the Philippines and Marianne Islands and to the south of the Galapagos group. It is made up to a large extent of the siliceous frustules of diatoms. It is usually yellowish-grey and often straw-coloured when wet, though when dried it becomes white and mealy.
Radiolarian ooze was recognized as a distinct deposit and named by Sir ' John Murray on the " Challenger " expedition, but it may be viewed as red clay with an exceptionally large proportion of siliceous organic remains, especially those of the radiolarians which form part of the pelagic plankton.
Systematic quarrying of siliceous crystalline rocks in New England began at Quincy in about 1820.
About nine-tenths of the gold was got from dry or siliceous ores and about 8% from placer mines; about twothirds of the silver from dry or siliceous ores, about two-ninths from copper ores, and most of the other ninth from lead ores.
Rhaetic beds (Infra Lias), consisting of dolomites and siliceous limestones, have been recognized at Saida.
The lower and middle divisions of the Jurassic, composed of massive limestones more or less siliceous and overlain by the marls amd highly fossiliferous limestones of the Upper Lias, play an important part in the constitution of the chief mountains of the Tell.
It contains much volcanic material, and great bodies of siliceous shale, locally estimated at 4000 ft.
The mercurial ores of the Pacific Coast ranges occur in very irregular deposits in the form of strings and bunches, disseminated through a highly metamorphosed siliceous rod~c. The first locality where the metal was successfully mined was at New Almaden, about 100 m.
North of the mineral region is the "Cereal Belt," embracing the Tennessee Valley and the counties beyond, whose richest soils are the red clays and dark loams of the river valley; north of which are less fertile soils, produced by siliceous and sandstone formations.
The surface soil is clay in which are embedded fragments of siliceous sandstone, used for millstones and constructional purposes; the subsoil is limestone.
Weed, "Formation of Travertine and Siliceous Sinter by the Vegetation of Hot Springs," in the 9th Annual Report of the Director of the United States Geological Survey (Washington, 1889); descriptions in the 5th, 6th and 12th Reports of the Hayden Geological and Geographical Survey of the Territories (ibid., 1871, 1872 and 1878); J.
In the pine forests of the Alps the prevailing species are the common spruce and the silver fir; on siliceous soil the larch flourishes, and surpasses every other European species in height.
The more argillaceous and the less siliceous the soil the more readily can balls of earth be retained about the roots.
They extend back beyond the Carboniferous, where they occur as hyphae, &c., preserved in the fossil woods, but the best specimens are probably those in amber and in siliceous petrifactions of more recent origin.
Siliceous; and the dephosphorizing or " Thomas " or " basic Bessemer " process, so called because the converter is lined with basic materials, usually calcined dolomite, a mixture of lime and magnesia, bound together with tar, and because the slag is made very basic by adding much i?`- -, - .1 -?=Woi krii fr ?`?'??-«:: e i h ..
When the former is used it is roasted with calcium sulphate or alkali waste to form a matte which is then blown in a Bessemer converter or heated in a reverberatory furnace with a siliceous flux with the object of forming a rich nickel sulphide.
The process adopted for the Canadian ores, which are poor in copper and nickel, consists in a preliminary roasting in heaps and smelting in a blast furnace in order to obtain a matte, which is then further smelted with a siliceous flux for a rich matte.
The coarse-metal is now smelted, with coke and siliceous fluxes (in order to slag off the iron), and the product, consisting of an impure copper sulphide, is variously known as " blue-metal," when more or less iron is still present, " pimplemetal," when free copper and more or less copper oxide is present, or " fine " or " white-metal," which is a fairly pure copper sulphide, containing about 75% of the metal.
Antimony, however, occurs chiefly as the sulphide, stibnite; to a much smaller extent it occurs in combination with other metallic sulphides in the minerals wolfsbergite, boulangerite, bournonite, pyrargyrite, &c. For the preparation of metallic antimony the crude stibnite is first liquated, to free it from earthy and siliceous matter, and is then roasted in order to convert it into oxide.
This substance, which has been found to be a purely siliceous concretion, is possessed of peculiar optical properties.
The outer cuticle of Oriental species is so hard that it forms a sharp and durable cutting edge, and it is so siliceous that it can be used as a whetstone.