Book on Fossil Objects, Stones, and Gems

On the specific markings of stones

Now let us move to specific details.

Markings or "spots" original: maculae are larger than simple dots. We read that Ophites original: Ophiten; a green stone named after the Greek ophis for snake, today known as serpentine is a green marble, usually covered entirely with white spots, though sometimes marked with other colors. Porphyry original: porphyriten; a hard igneous rock prized in antiquity for its deep purple-red color, on the other hand, is varied with red and almost white spots, or rather it is a red stone with spots shining through it, and so forth.

Pliny Gaius Plinius Secundus (AD 23–79), the Roman author of Natural History, the most influential source for Renaissance mineralogy. seems to also use the term "boundary" original: limitem to describe a line in stones. Other terms used for such features include "thread," "streak," "belt," or "vein"—similar to the "comb" or grain found in wood. The Greeks call this a gramme original: γραμμὴν; a line or stroke and some call it a diaphysis original: διάφυσιν; a natural division, gap, or joint between parts.

However, some lines are visible only because of their color. In solid substances, these are called schista original: σχιστὰ; meaning split or fissile, that is, "splittable" stones. Their entire body appears to be composed of touching lines, as seen in various types of alum and hematite original: haematitae; an iron ore often occurring in fibrous or "kidney" shapes, as well as in asbestos original: amianto; a fibrous mineral known since antiquity for being fire-resistant, antimony original: stibio, sal ammoniac original: sale Ammoniaco; a rare natural mineral composed of ammonium chloride, often found around volcanic vents, and several others. Indeed, one specific type of hematite is known par excellence by this very name, schistos original: σχιστὸς; fissile or split-stone, because...

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