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Distinctly crystalline; -- used of rocks. Opposed to Ant: cryptocrystalline.

genus Pholas, or family Pholadidæ. They bore holes for themselves in clay, peat, and soft rocks.

A compact, feldspathic, igneous rock containing nephelite, haüynite, etc. Thin slabs give a ringing sound when struck; -- called also clinkstone.

A dark green igneous rock, consisting largely of chrysolite, with hornblende, augite, biotite, etc.

The pilot's skill or knowledge, as of coasts, rocks, bars, and channels. [Obs.] Sir W. Raleigh.

The sharp-tailed grouse of the great plains and Rocky Mountains (Pediocætes phasianellus); -- called also pintailed grouse, pintailed chicken, springtail, and sharptail.

c. -- Pitch chain, a chain, as one made of metallic plates, adapted for working with a sprocket wheel. -- Pitch line, or Pitch circle (Gearing), an ideal line, in a toothed gear or rack, bearing such a relation to a corresponding line in another gear, with which the former works, that the two lines will have a common…

Having the arris defined by a line beyond which the rock is cut away, so as to give nearly true edges; -- said of squared stones that are otherwise quarry-faced.

An igneous rock of semiglassy nature, having a luster like pitch.

the influence of volcanic heat and other subterranean forces under pressure. -- Plutonic rocks (Geol.), granite, porphyry, and some other igneous rocks, supposed to have consolidated from a melted state at a great depth from the surface. Cf. Intrusive rocks, under Intrusive. -- Plutonic theory. (Geol.) See Plutonism.…

The theory, early advanced in geology, that the successive rocks of the earth''s crust were formed by igneous fusion; -- opposed to the Neptunian theory.

A cavity in a rock containing a nugget of gold, or other mineral; a small body of ore contained in such a cavity.

Mottled with various colors; variegated; spotted; -- said of certain rocks.

Sharp; having a sharp point; as, a pointed rock.

ridges. [R.] Now had they brought the work by wondrous art Pontifical, a ridge of pendent rock Over the vexed abyss. Milton.

A rock with a porphyritic structure; as, augite porphyrite.

A term used somewhat loosely to designate a rock consisting of a fine-grained base (usually feldspathic) through which crystals, as of feldspar or quartz, are disseminated. There are red, purple, and green varieties, which are highly esteemed as marbles. Porphyry shell (Zoöl.), a handsome marine gastropod shell (Oliva…

A circular hole formed in the rocky beds of rivers by the grinding action of stones or gravel whirled round by the water in what was at first a natural depression of the rock.

One who hawks crockery or earthenware. [Prov. Eng.] De Quincey.

A pounded or pulverized substance. [R.] "Covered with the poundings of these rocks." J. S. Blackie.