(c.232–303), Neoplatonist philosopher; born Malchus. He was a student of Plotinus, whose works he edited after the latter's death.
A hard igneous rock containing crystals, usually of feldspar, in a fine-grained, typically reddish groundmass.
- ‘They also noted that much kaolin is in or near decomposed porphyry bodies that overlie the largest ore shoots in the Leadville Dolomite.’
- ‘A porphyry obscures the contact between the Cross Slieve Group and the Red Arch Formation.’
- ‘During this time, many of the district's steeply dipping, northeast-trending faults were intruded by narrow, granodiorite porphyry dikes.’
- ‘The mine workings occupy much of the west side of an isolated low hill composed mainly of light-colored volcanic rock, described as felsite porphyry or trachyte, highly altered to clay minerals.’
- ‘This mine, just north of the Mount Tolman porphyry molybdenum-copper deposit, was once Washington State's sole fluorite producer, with 235 tons shipped between 1918 and 1940.’
- ‘The ore is associated with plagiogranite porphyry of Mesozoic age.’
- ‘Although closely associated with plutonic igneous rocks, porphyry mineralization commonly encompasses large volumes of the surrounding host rocks to the intrusion.’
- ‘This rare work of porphyry, limestone, serpentine and onyx is unique north of the Alps.’
- ‘Final polishing will only succeed on the hardest of stones, such as granite, porphyry, and gemstones, and again abrasive materials will be used for this, including abrasive powders or salts.’
- ‘The reference to emerald stone probably indicates color rather than medium, which suggests that the statue was carved of green basalt, granite, porphyry, or serpentine.’
- ‘The fault places massive fractured greenstones over relatively undeformed feldspar andesite porphyry.’
- ‘In 2000, fifty porphyry deposits had been identified in Chile, with reserves of 400 million tons of copper!’
- ‘The sedimentary beds are composed mainly of poorly sorted subangular to rounded clasts of felsite and rhyolite porphyry that are typically a red color.’
- ‘At least two Eocene feldspar porphyry dykes or sills intrude Tsa da Glisza, and appear to have followed the same planes of weakness as the aplite dykes.’
- ‘This is particularly well known to collectors familiar with porphyry copper deposits of Arizona, New Mexico, and Utah.’
- ‘Some of the finest cuprite specimens ever found have come from the oxidized zones of several of Arizona's porphyry copper and related deposits.’
- ‘Other possible occurrences include porphyry copper deposits that contain enargite at depth, such as Chuquicamata, Chile.’
- ‘The Main Channel conglomerate is made up of a variety of well-rounded felsite, granophyre, and quartz-feldspar porphyry pebbles, suggesting a geologically diverse source terrane.’
- ‘The Henry Mountains consist of multiple intrusions of quartz-monzonite porphyries (predominantly plagioclasehornblende rocks) that were emplaced from 29.2 to 20.0 million years ago into a thick sequence of Mesozoic sediments.’
- ‘Most beds are almost monomictic, comprising quartz-feldspar porphyry clasts, whereas some other beds are highly heterogeneous.’
Late Middle English: via medieval Latin from Greek porphuritēs, from porphura purple.
We take a look at several popular, though confusing, punctuation marks.