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Mineral deposits and rock masses designated with reference to their origin; as, the siliceous formation about geysers; alluvial formations; marine formations.

The siliceous shell of a diatom. It is composed of two valves, one overlapping the other, like a pill box and its cover.

A refractory material consisting of crushed or ground siliceous stone, mixed with fire clay; -- used for lining Bessemer converters; also used for macadamizing roads.

brought from Japan. It has a long stem, consisting of a bundle of long and large, glassy, siliceous fibers, twisted together.

A siliceous sponge, of the genus Hyalonema, and allied genera; -- so called from their glassy fibers or spicules; -- called also vitreous sponge. See Glass-rope, and Euplectella.

A hard, coarse-grained siliceous sandstone; as, millstone grit; -- called also gritrock and gritstone. The name is also applied to a finer sharp-grained sandstone; as, grindstone grit.

An order of sponges, having simple siliceous spicules and keratose fibers; -- called also Keratosilicoidea.

Belonging to the Hexactinellinæ, a group of sponges, having six-rayed siliceous spicules.

erithium, and allied genera. -- Horn silver (Min.), cerargyrite. -- Horn slate, a gray, siliceous stone. -- To haul in one's horns, to withdraw some arrogant pretension. [Colloq.] -- To raise, or lift, the horn (Script.), to exalt one's self; to act arrogantly. "'Gainst them that raised thee dost thou lift thy horn"…

A siliceous stone, a variety of quartz, closely resembling flint, but more brittle; -- called also chert.

f hexactinelline sponges, having a long stem composed of very long, slender, transparent, siliceous fibres twisted together like the strands of a color. The stem of the Japanese species (H. Sieboldii), called glass-rope, has long been in use as an ornament. See Glass-rope.

An order of vitreous sponges, having glassy six-rayed, siliceous spicules; -- called also Hexactinellinæ.

usoria; as, infusorial earth. Infusorial earth (Geol.), a deposit of fine, usually white, siliceous material, composed mainly of the shells of the microscopic plants called diatoms. It is used in polishing powder, and in the manufacture of dynamite.

A laminated, granular, siliceous rocks, often occurring in regions where the diamond is found.

A compact siliceous rock resembling jasper.

Siliceous earth; specifically, porous infusorial earth, used as an absorbent of nitroglycerin in the manufacture of dynamite.

A variety of siliceous slate, of which hones are made; razor stone; Turkey stone; hone stone; whet slate.

rocks situated below the rocks of the Carboniferous age and comprising various strata of siliceous sandstones and conglomerates. See Sandstone, and the Chart of Geology. -- Old school, a school or party belonging to a former time, or preserving the character, manner, or opinious of a former time; as, a gentleman of t…

Order of rhizopods, usually having a siliceous skeleton, or shell, and sometimes radiating spicules. The pseudopodia project from the body like rays. It includes the polycystines. See Polycystina.

n the arts, and for cleaning metallic substances. The name is also given to other friable siliceous stones applied to like uses.