porphyritic

You can find dwarfs, hobbits, dragons and wizards in the towers created by porphyritic lava flows.

The dark-coloured porphyritic crystals of basalts are known as basaltic hornblende.

At Port St. Julian, the country becomes hilly, and continues so as far to the northward as latitude 44�, the rock being porphyritic.

His marble was perhaps the porphyritic rock which it resembles when wetted by sea moisture.

Those rocks examined microscopically consist of basalts which are often porphyritic.