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The state or quality of being metamorphic; the process by which the material of rock masses has been more or less recrystallized by heat, pressure, etc., as in the change of sedimentary limestone to marble. Murchison.

An alteration in a mineral or rock mass when involving a chemical change of the substance, as of chrysolite to serpentine; -- opposed to ordinary metamorphism, as implying simply a recrystallization. -- Met`a*so*mat"ic, a.

A granitoid rock containing feldspar, biotite, elæolite, and sodalite.

A minute inclosed crystal, often observed when minerals or rocks are examined in thin sections under the microscope.

f double image micrometer, in which the two images are formed by the double refraction of rock crystal. -- Filar, or Bifilar, micrometer. See under Bifilar. -- Micrometer caliper or gauge (Mech.), a caliper or gauge with a micrometer screw, for measuring dimensions with great accuracy. -- Micrometer head, the head o…

A rock showing under the microscope the structure of a graphic granite (pegmatite). -- Mi`cro*peg`ma*tit"ic, a.

k of a plant, or a series of cells, in which the milky juice is contained. See Latex. -- Rock milk. See Agaric mineral, under Agaric. -- Sugar of milk. The sugar characteristic of milk; a hard white crystalline slightly sweet substance obtained by evaporation of the whey of milk. It is used in pellets and powder as a…

An excavation in rock, transverse to the workings, from which material for filling is obtained.

n nature, having a definite chemical composition and usually a distinct crystalline form. Rocks, except certain glassy igneous forms, are either simple minerals or aggregates of minerals.

h American rodent (Cavia rupestris), allied to the Guinea pig, but larger; -- called also rock cavy.

A soft Tertiary sandstone; -- applied to a rock occurring in Switzerland. See Chart of Geology.

An order of large, extinct, marine reptiles, found in the Cretaceous rocks, especially in America. They were serpentlike in form and in having loosely articulated and dilatable jaws, with large recurved tteth, but they had paddlelike feet. Some of them were over fifty feet long. They are, essentially, fossil sea serpen…

g the spores. There are many species, collectively termed Musci, growing on the earth, on rocks, and trunks of trees, etc., and a few in running water.

A mass of earth, or earth and rock, rising considerably above the common surface of the surrounding land; a mountain; a high hill; -- used always instead of mountain, when put before a proper name; as, Mount Washington; otherwise, chiefly in poetry.

A large mass of earth and rock, rising above the common level of the earth or adjacent land; earth and rock forming an isolated peak or a ridge; an eminence higher than a hill; a mount.

An optical phenomenon sometimes seen on the summit of mountains (as on the Brocken) when the observer is between the sun and a mass of cloud. The figures of the observer and surrounding objects are seen projected on the cloud, greatly enlarged and often encircled by rainbow colors.

Fortification; stronghold. [Obs.] His place of defense shall be the munitions of rocks. Is. xxxiii. 16.

having rough, and frequently spinose, shells, which are often highly colored inside; the rock shells. They abound in tropical seas.

o have been partly the gum above named, and partly the exudation of species of Cistus, or rockrose. False myrrh. See the Note under Bdellium.

le hydrocarbons, occurring naturally, and usually called crude petroleum, mineral oil, or rock oil. Specifically: That portion of the distillate obtained in the refinement of petroleum which is intermediate between the lighter gasoline and the heavier benzine, and has a specific gravity of about 0.7, -- used as a solve…