I once had the pleasure of quarrying alongside a delightful gentleman wielding what he said was a self-sharpening pick with a 12 pound head. Though I did not investigate the particulars of the tool at the time--except to note that both striking ends remained exceptionally keen in extended use and necessarily wore protective covers when we adjourned for the night--dulling experience with my own tools gave later pause to ruminate on its makeup.
My over-thinking speculation was that a tool with progressively softer layers of steel alloys radiating out from the harder core could form the material for such an implement. But my Internet searches over time for either a historical exemplar, available modern pick or other excavating hand tool of such self-sharpening nature proved unavailing.
An immediate and unexpected stimulus to this post was a provocative article on the discovery of self-sharpening teeth in sea urchins, the text of which appeared in "Science Daily" seen at:
The urchin teeth differ from my naive preconception in that the hard hard layers in the structure all of the same durability among which are interspersed eroding soft layers.
This idea and its reality is elegant for simplicity. Because the leading striking edge of a penetrating implement wears first and the most during use, it is now clear how this would result in a taper both in a pick and urchin tooth.
If anyone can either generally corroborate and specifically describe occurrences of such self-sharpening mining tools (a hefty pick foremost) or give me a pointer to any current manufacturers whom might provide more information or the implements themselves, I would be grateful.
Advance thanks to all for any direction.
Regards,
Edward Hennessey