The Indians themselves were dexterous in taking out gold.

Columbus added to their number seventy-five men.
In one day's work, they obtained "two or three castellianos" without much difficulty.

A castelliano was a gold coin of the time, and the meaning of the text is probably that each man obtained this amount.

It was one of the "placers," such as have since proved so productive in different parts of the world.
Columbus satisfied himself that there was a much larger population inland.

He learned from the Indians that the cacique, as he always calls the chief of these tribes, was a most important monarch in that region.
His houses were larger than others, built handsomely of wood, covered with palm leaves.
The product of all the gold collected thus far is stated precisely in the official register.