PORPHYRITIC • FREE-TRANSLATOR.COM • Definition of Porphyritic

... that at Tette, and quite metamorphosed where it comes into contact with the igneous rocks below it. It sometimes gives place to quartz and reddish clay schists, much baked by heat. This is the usual geological condition on the right bank of the Cataracts. On the other side we pass over masses of porphyritic trap, in contact with the same mica schists, and these probably give to the soil the great fertility we observed. The great body of the mountains is syenite. So much mica is washed into the river, that on looking attentively on the stream one sees myriads of particles floating and glancing ...

— A Popular Account of Dr. Livingstone's Expedition to the Zambesi and Its Tributaries • David Livingstone

... close up to it stand the famous blue-stones, now twelve in number, but originally perhaps more. These stones are not so high as the trilithons, the tallest reaching only 7-1/2 feet. They are nearly all of porphyritic diabase. It has often been asserted that these blue-stones must have been brought to Stonehenge from a distance, as they do not occur anywhere in the district. Some have suggested that they came from Wales or Cornwall, or even by sea from Ireland. Now, ...

— Rough Stone Monuments and Their Builders • T. Eric Peet