metalpoint

"Metal point,  descendant of the stylus of classical times and ancestor of the modern pencil, a small, sharpened metal rod used for drawing precise compositions on paper or parchment. The metal could be lead, silver, copper, or gold, but silverpoint was the most common choice because it is the most suited to permanent drawing, its stroke adhering unerasably. The silverpoint was of great value in producing the hard, clearly defined line required, for instance, by miniaturists; modelling, emphasis, and light phenomena, however, had to be rendered either by means of repetitions, dense hatching, or blanks or else supplemented by other mediums." — Encyclopaedia Britannica (online), 1996.  

The silverpoint drawing ground creates a slightly rough surface onto which the metal particles rub off . The wire can be of  different metals but I tried silver which was relatively inexpensive. I also bought a wire holder (right) a sort of pin vice.

The ground is the consistency of thin cream.. I was impatient to get going so grabbed some scrap paper giving it two coats .. although three would have been better.

I found the holder heavy, a bit cumbersome and uncomfortable to draw with.

As the wire is 0.5 mm and the same size as a pencil lead it easily loaded into mechanical pencil. 

The metal point performed slightly differently to lead- it felt grittier but produced softer lines. It didn't really erase well but marks didn't smudge either.It took several layers to get darker tones. Apparently the silver tarnishes over time to a warm brown. I was pleased with the results considering it was a quick sketch on scrap paper.. Definitely something else I shall be experimenting with in the near future. 
There is a great website with a lot of useful info here.