The World Of Khoras - Physical World - Mineralogy - Stones and Rocks

Ebony Granite

A black rock found primarily in the Sentinel Mountains. It is dense, heavy and very hard. Its great strength resists cracking and weathering. Rathani is extremely effective at blocking magical energy (with only a few inches thickness) and so is greatly prized. Rathani is extremely rare and found only at great depths beneath the surface. It forms only under great heat and pressure.

Ebony granite is 10% effective at blocking magical energy per inch of thickness. Therefore, a slab of ebony granite 10 inches thick would effectively block all magical energy. A 10 inch thick layer of ebony granite on all walls, floor and ceiling of a room would shield the room from all spells. But the cost and rarity of ebony granite makes this impractical.