Watch List notes:

Bronze mariner's astrolabe in coral matrix (as found), probably Spanish, ca. 1580. 3660 grams, 7" in diameter (10" x 8" x 3" overall). The mariner's astrolabe was an early navigational device for determining latitude based on astronomical observation, specifically in replacement of the more cumbersome quadrant (which was impossible to use accurately on a rocking ship), and very few astrolabes are known to exist, generally named and documented by experts. The overall shape of the device is round with open quarters, with a suspension ring at top and a rotating alidade in the center for measurement, but most salvaged specimens from shipwrecks (which, incidentally, is where most of the known specimens originated) lack the ring and alidade, as is the case here. The surfaces of this piece are very worn and corroded (no markings visible), even a bit rusty and patinated, but what is unique about this piece is the fact that a large head of coral has grown around its various open spaces, holding it in place (albeit loosely) and creating an interesting natural display-stand for the astrolabe. Pedigreed to our Auction #3, lot #937. Recovered from: Unidentified late-1500s wreck off Crocker Reef in the Florida Keys

Estimate: $20000