Kaf
According to the Musulmans, a great mountain that stretches to the horizon on every side. The earth is in the middle of this mountain, they say, like a finger in the middle of a ring. Its foundation is the stone Sakhrat, the least fragment of which is capable of working untold marvels. This stone it is which causes earthquakes. It is made of a single emerald. The mountain, which is frequently spoken of in Eastern tales, is said to be the habitation of genii. To reach it one must pass through dark wildernesses, and it is essential that the traveller be guided by a supernatural being. "