Note 10 — GOLD, SILVER, AND JEWEL WORK

“In Spain,” said Bowles (Hist. Nat. de Esp., p. 498), “are found two species of rock crystal. The one, occurring in clusters, are transparent, six-sided, and always have their source in rocks. There are great quantities all over the kingdom, and at Madrid they are found near the hills of San Isidro. The other species are found singly, and are rounded like a pebble. I have seen them from the size of a filbert to that of my fist. Some were covered with a thin, opaque integument…. The river Henares abounds with these crystals, and as it passes San Fernando, at two leagues' distance from Madrid, sweeps some of them along which are the size of the largest ones at Strasburg, though very few are perfect.”