plumbago

We have likewise found a vein of plumbago, which was an object of search, on the supposition that it was coal.

Red hermatite, iron ore, traces of copper, and plumbago are found along the main Bitter Root.

Even fresh, natural fruits that have been evenly coated with plumbago may be covered with a thin shell of metal.

Iron acquires some little weight by being converted into steel; and when dissolved in acid, it yields more plumbago.

The most common solid employed as a lubricant is graphite, sometimes termed “plumbago” or “black lead.”