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14
DE NATURA FOSSILIUM
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Nature
has given minerals various shapes and forms with the exception of the
earths which are either without form or are tabular, for example,
Samian aster. Some minerals are round. Thyites found
between Syene and Philae occurs in perfect spheres while stones from
veins that are carried along by rivers and deposited on the banks occur
as compressed spheres with protuberances and hollows. Turquois and astroites occur in hemispheres while beryl and syenites are
cylindrical. Some are conical and others have the shape of a top.
Certain stones and congealed juices similar to icicles which form in
caves represent the former; those which hang from the backs of caves,
the latter. Some minerals are angular. They may be either triangular
such as certain gems; quadratic or cubic as diamond and some pyrite
found in rivers and brooks; or pentagonal as the Misena basaltes, although this may have a variable number of angles from four to seven. Quartz has six angles and pangonius many angles.3
Some minerals have a hexagonal termination which is common on quartz
and found occasionally on diamond. Others with a spindle shape have
been twisted into the form of a snail's shell, for example, some stones.
Selenite and magnetis are flat; geodes, convex on the inner side; smarag-dus, concave. Minerals may be covered with wart-like excrescences as is myrmecias. Some have forms which imitate those of well known objects. Ammonis cornu imitates a horn; tephrites, a new moon; alum, asbestos, and native silver, hair; some stones similar to gems, the lobe of the ear; bu-cardia, the heart of an ox; some pyrite, a honeycomb;4 African sand, pebbles from near the pyramids in Egypt and Cappadocia Hill, lentils; stele-chiles, the trunk of a tree; belemnites, an arrow; chalazias, hail; lapis judaicus, an acorn; lapis molaris found near Volsinii, a mill-stone; rocks in Hildesheim, a beam of wood; Misena and Syene basaltes, an upright piece of wood. Certain others represent effigies of things, for example, enorchis, the testes; diphyis, the genitals of both sexes; entrochos, a wheel; enostos, bones. According to Pliny, when cyamea is
crushed it breaks into pieces which resemble beans. Certain rocks, when
split open, are found to contain shells, for example, the conchites beds
of Megara and the rocks of France which contain snail shells.
Inclusions in transparent amber are conspicuous. These embrace gnats,
fleas, ants, spiders, small fish, fish eggs, leaves of trees, stalks of
plants, seaweed, and other small things. These were entangled in the
amber when it flowed down from higher ground into the sea and even in
the sea itself before congelation. This happened by accident and
certainly on the surface of the earth.
Going back to minerals, many with lines of various colors running through them resemble various objects as leucophthalmos resembles the
' Agricola, following the Greeks, gives the name pangonius to twelve-sided and complex quartz crystals. In "Interpretatio Germanica Vocum Rei Metallicae" he classifies pangonius and quartz as the same mineral.
*
This is a good description of a well-known and wide-spread
pyrite-marcasite texture formed by the primary alteration of pyrrhotite.
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