The Paiutes of western North America are in Volcano country. In ancient times the shaman would take pottery to the flowing lava, cast the pottery into the lava so it would break, then withdraw the pottery covered with sacred lava.
In most cultures of the American Southwest and central America, the god of fire is the original god. The Aztecs of Mexico called him Grandfather Fire.
Aztec statues of grandfather fire had a basin on top of his head where fire would burn. To this day, statues of Grandfather Fire in the temples of the native Huichol people of the Sierra Madre Mountains (Mexico), a statue of grandfather fire is placed in the center of a ceremonial fire ring that burns over another statue of grandfather fire that is buried under the ring. From time to time, the idol underground is excavated and inspected. If it is badly damaged, a new one is made and buried in its place.
Earth is mother. Imagine how sexy is the lava which is a combination of fire and earth. How hot that combo is that it spits volcanic rock over the landscape for miles in all directions. Insert passionate music here.
Carving a sacred image on the body of volcanic rock is making an extraordinarily powerful prayer.