These basalt-columns are very regular, with from five to eight sides; and are almost black in colour.

They have a curiously well-defined circular core in the middle, five or six inches in diameter.

This core is light grey, almost white.

The Indians bring down numbers of short lengths or joints of the columns, and they are used at the hacienda in making a primitive kind of ore-crushing mill, in which they are dragged round and round by mule-power, on a floor also of basalt.
When we had visited the falls we took leave of our hospitable friend, and set off to return to the Real.

We stopped at San Miguel, another of the haciendas of the Company, where the German barrel-process is worked.