A porphyritic dyke runs along the Pacific slope and tends to change the direction of the veins of ore.
Page 40: "porphorytic" changed to "porphyritic" (the greenstone is handsomely porphyritic).
Transitions to the porphyritic dolerites and basalts arise by increase in the proportion of this ground-mass.
porphyritic mountains, says M. Maury, imprint on the landscape a peculiarly picturesque character.
In the main the lava is an andesite, and is very generally of a porphyritic structure.
The shales become dense, highly crystalline rocks of a "hornstone" type, with porphyritic developments of silicate minerals.
That is, the metamorphic rocks are characteristically holocrystalline, while igneous rocks are porphyritic, or cryptocrystalline.
The sands and sandstones become highly crystalline quartzites, spotted with porphyritic developments of silicates.
But the bulk of the moraine is composed of porphyritic granite derived from Feldspar and Cathedral Valleys.
Subsequently the porphyritic rock flowed over the surface in a pasty mass, covering the limestone.