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DE NATURA FOSSILIUM
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are yellow. A certain variety of earth (rubrica) is red whence comes its name. Sard and carbunculus are red. Realgar has a ruddy color while amethyst is purple.
There are marked differences in shades of color in all of these minerals. For example, among the green minerals smaragdus is
an intense green, chalk, pale green and chrysocolla an intermediate
shade. Certain minerals have their own distinctive colors such as lead
which is neither black nor blue-black and pure copper, between ruddy
and red. Some minerals imitate the colors of other minerals and
metals. Orpiment and yellow musco-vite imitate the color of gold; one
variety of aspilates, silver; chalcitis, copper; one variety of balanites, Corinthian copper; galena, lead; dactylus idaeus and basaltes, iron. Several minerals imitate the color of living things. For example, the gem icterias is similar in color to saffron; hematite, to blood; prasius, to the leek; aspilates, to fire.
Many minerals have two mixed or separate colors. Taking up those with mixed colors first, some are bluish white such as jaspis which is also called borea. Some are greenish blue such as armenium, some whitish red, as aphrodisiace. Some minerals are in part yellowish white as xanlhos; in part blackish red such as the three varieties of batrachites. Certain black minerals have a purplish tinge, for example alabandicus lapis.
Regarding
minerals with two separate colors, those having white and black bands
have been used more than all others in our times since they are so
admirably suited for carving. These stones occur in nature with
alternating white and black bands. Apsyctos has a black groundmass cut by red veins while nasamonites has a red groundmass cut by black veins. Leek-green heliotropios is cut by blood-red veins. Lapis lazuli contains sparkling golden points of light.
Some
minerals have three separate colors. Stones found in glass sands are
white, red and yellow; white, gray and black; even white, green and
blue. The white groundmass of the mineral "Egyptian agate" is cut by
black and sard-red veins according to Jacchus. Eupetalos and orca have four different colors, eupetalos, blue, flame-red, vermillion and green; orca, black, dark yellow, green and white. Hexacontalithos and panchros have
even a greater number of distinct colors and the names of these stones
come from the variety of colors they show. If different color
combinations are found in stones such as these latter ones they do not
form new varieties but if such variations occur in other minerals they
usually do. Finally, several minerals such as the mineral paederos show
a play of colors similar to that seen on the neck feathers of certain
African fowl when ruffled in anger and on the feathers of the peacock
or pigeon when spread in the sun. These minerals also show a play of
colors when inclined in different directions.
Although
certain minerals are transparent most minerals are not. None of the
earths, metals, or rocks is transparent. Out of the large number of
mixed minerals proustite is the only transparent one, a deep red, and
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