American Heritage® Dictionary of the English Language, Fourth Edition
- n. Rock containing relatively large conspicuous crystals, especially feldspar, in a fine-grained igneous matrix.
Century Dictionary and Cyclopedia
- n. The English form of Latin word porphyrites, used by the Romans to designate a certain rock having a dark-crimson ground through which are scattered small crystals of feldspar. In Pliny's time this rock, which was quarried in Egypt, was used extensively for architectural and ornamental purposes, and especially for the base or lower part of busts of which the upper part was made of bronze or marble. Later on, a similar stone appears to have been procured from nearer localities, as from the island of Sardinia. To the Italians it became known as porfido rosso antico. Other rocks having a similar structure, commonly called
porphyritic, were used in Italy, and designated, in accordance with the predominating color, as porfido nero, porfido verde, etc. In modern times the term porphyry has come to be used as the name of any rock consisting of a very fine grained or microcrystalline ground-mass through which are disseminated distinctly recognizable crystals of some mineral; but the popular use of the word is frequently extended so as to include rocks which are dark-colored, fine-grained, and very hard, and which do not appear to belong either to the marbles or granites, and this is done even when the porphyritic structure is not at all or only very indistinctly marked. The varieties of porphyry are numerous, and their nomenclature by no means definitely established. The most generally accepted are the following: quartz-porphyry, of which the ground-mass consists of an intimate or cryptocrystalline admixture of orthoclase and quartz, in which distinct crystals or large grains of quartz are developed; feldspar, felsitic or felstone porphyry, having a similar base with porphyritically inclosed crystals of feldspar, which is commonly orthoclase; but similar crystals of this mineral are not infrequently found occurring with the quartz in quartz porphyry, so that no very distinct line can be drawn separating the two varieties mentioned. These porphyries are of most frequent occurrence in the Paleozoic rocks, but they are also found in abundance in other Pre-tertiary formations, presenting the characters of a truly eruptive material. See porphyrite, and cut under porphyritic.
- n. A slab of porphyry, used in alchemy.
- n. In zoology, a porphyry-moth.
- n. In ceramics, a hard colored body made by Josiah Wedgwood, in imitation of porphyry.
GNU Webster's 1913
- n. (Geol.) 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.
- n. any igneous rock with crystals embedded in a finer groundmass of minerals
- Middle English porphiri, porfurie, from Old French porfire, from Italian porfiro, from Medieval Latin porphyrium, from Latin porphyrītēs, from Greek porphurītēs, from porphurā, shellfish yielding purple dye, purple (from its color). (American Heritage® Dictionary of the English Language, Fourth Edition)
“Rhenium is obtained almost exclusively as a by-product of the processing of a special type of copper deposit known as a porphyry copper deposit.”
“When the Pope leads Mass at the newly complete altar - made, as part of Bonet's design, from a purplish stone called porphyry - 6,500 faithful, including 1,000 priests, will pray with him.”
“The so-called porphyry copper mines, which now produce more than half the world's copper, are worth looking at in the context of exploitation limits.”
“Throughout the week, unusually large amounts of crustae (marble revetment slabs) have been found that are mainly composed of green-white cipollino from Euboia, purple veined pavonazetto marble from Dokimeion, white marble, and even some small pieces of red porphyry, which is a type of igneous rock.”
“There was also a very hard variety of granite much used by sculptors called porphyry, a very hard and variegated rock of a mixed purple-and-white colour.”
“The principal measured reserves are in the so-called porphyry coppers of the United States and Chile.”
“Between every tower, in the midst of the said body of building, there was a winding stair, whereof the steps were part of porphyry, which is a dark-red marble spotted with white, part of”
“The porphyry, which is of warm brown or chocolate colour, includes many crystals of lighter coloured felspar, and dark crystals of hornblende.”
“The great calendar-stone, which in 1790 was disinterred in the city of Mexico, was nicely wrought out of a block of dark porphyry, that is estimated to have weighed fifty tons, and must have been transported several leagues; for the nearest point where porphyry of that character is found is upon the shores of Lake Chalco, many miles distant from the city of Mexico.”
“If these parts of the composition be less distinct, or if only two of them be visible to the eye, it is termed porphyry, trap, whinstone, moorstone, slate.”
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From the GNU Webster's 1913:
"n. A massive, compact limestone; a variety of calcite, capable of being polished and used for architectural and ornamental purposes. The color varies from white ...
Words rounded up while reading The Innocents Abroad by Mark Twain.
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