The copper veins are abundant in the killas and rare in the granite; but most numerous near the line of junction of the two rocks.
The extensive spread of Killas is not, however, entirely Devonian, as it is shown on most maps.
To the granite Cornwall owes much of its prosperity; it has altered the Killas for some distance around each mass, and the veins of tin and copper ore, though richest in the Killas, are evidently genetically related to the granite.
Thus many lodes which yield abundance of ore in granite, are unproductive in clay- slate, or killas and vice versa.
This killas is converted into hornblende-schist near the contact with the veins.
The same observation applies to killas and the granitic porphyry called elvan.
Sometimes, in the same continuous vein, the granite will contain copper, and the killas tin, or vice versa.
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "killas" in a variety of sentences. We hope that you will now be able to make sentences using this word.
