39. They are rather heavy in weight and have a strong odor.
The sulfides are distinguished as minerals by their moderately high specific gravity. The mention of odor also indicates that sulfide minerals are meant. Though the pure minerals are odorless, on oxidation they easily give rise to sulfur dioxide, and this has a characteristic odor which is sharp and disagreeable. The strong odor that arose from heating sulfide minerals was certainly well known to die ancients, as the operation must have been frequently performed in mining districts. At Laurion, for example, it is very probable that galena was roasted on a large scale as a preliminary step in the reduction of the ore.288 Furthermore, certain natural sulfides, such as marcasite, yield traces of sulfur dioxide and hydrogen sulfide when they are exposed to the weather, and their odors become strong when the minerals are broken. Both Dioscorides289 and Pliny290 allude to the disagreeable odor of certain partially decomposed sulfide minerals.
39. There is also natural kjanos which contains chrysokolla.
Theophrastus has just mentioned certain minerals or ores that resemble metals; he now proceeds in a characteristic way to mention certain ores that are unlike metals in appearance. From the notes on section 26 it will be seen that χρυσοκόλλα was a name used by Theophrastus for any bright-green copper mineral of an earthy nature. In this passage when he speaks of a blue mineral that contains a green copper mineral, the association of the two helps to fix the identity of both, since the only two ore minerals of these colors that are combined in this way are azurite, a darkblue basic copper carbonate, and malachite, a bright-green basic copper carbonate. These two are very commonly found together, often intermingled or superimposed on each other. Forms are also known that contain an inner core of malachite surrounded by azurite. Beautiful specimens of intermingled azurite and malachite have been found at Laurion. Malachite is the more abundant mineral of the two and is often found alone; with or without the
288 Rickard, Man and Metals, Vol. I, p. 381.
289 V, 118 (Wellmann ed., V, 103). 29° XXXIV, 120.
