Steel wheat penny at Central Jersey Rare Coins Blog.
Metallic Trees
The Lead Tree is produced as follows: Put into a glass bottle about half an ounce of sugar of lead, and fill up to the neck with distilled or rain water; then fasten to the cork or stopper a piece of zinc wire, so that it may hang in the centre; then place the bottle where it may remain undisturbed. The wire will soon be covered with crystals of lead, precipitated from the solution, and assuming a tree-like form, very pleasing to the eye.
The Corner Cupboard of Facts for Everybody by Robert Kemp Philip, 1859.
