Geographical Criteria for Producing Amber
Temperate to Tropical Climate.
Resin Producing Trees.
Burial of resin, (polymerization now started) before the resin physically and/or chemically breaks down, so the resin can begin to fossilize in a more anoxic environment.

Baltic Amber

The map above shows the areas, (purple line) where Baltic Amber is mined or recovered today.

Much of the primary Baltic Amber is found within a layer of "blue clay" which the sea is continually washing out and redepositing it on the shore line. This "redepositing" of the Amber makes the Amber found on shore a secondary deposit.