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Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica

Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Page of 251 Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Text size:minus plus Restore normal size   Mail page  Print this page
BOOK V
97
is free from all adhering earth it may be as white outside as inside. When split open it is light inside and glistens like marble and in some cases the outside also has a high luster. Having been powdered on a whetstone, as is customary since it is used in medicine, it has no taste. A piece the size of a chick-pea drunk with about a half ounce of hot water is prescribed in cases of difficult urination since it destroys gall-stones, more especially those in the kidneys than in the bladder.
Trochites is related to lapis judaicus and takes its name from a wheel. Since nature has given it the form of a drum the round part of it is smooth and each side has a certain degree of smoothness. Radii, so prominent they form striations, extend in all directions from the center to the outer rim like spokes in a wheel. It varies much in size but the smallest is about one tenth the size of the largest. The largest is the width of a finger in diameter and a third as thick. The color varies being either gray, black or yellow. This variety of colors is due to the contamination of earth since in the interior it is whiter than the rest of the material. It breaks, similar to lapis judaicus, along the length, width and obliquely and is smooth and brilliant inside. Having been placed in vinegar it gives off bubbles like astroites and sometimes possesses the same power to move itself from one place to another. Entrochos is sometimes formed from trochites by being built up of two, three, four or even more since as many as twenty are found joined together. There are two species of entrochos, one evenly rounded, the other evenly rounded but with the central part thickened and the edges constricted. These have the prominent radiating lines char­acteristic of trochites where two parts join on the curve of the girdle al­though the lower portions lack a girdle and are entirely smooth. The trochites are joined in such a fashion that the radii of one fits into the striae of the other. The thickened species usually have radii extending almost to the center. Often a shapeless stone is found associated with these minerals which contains within itself the form of a wheel which has remained in the stone as though it were the root of the mineral that had been broken off. These minerals occur in Saxony near Hildesheim on the last peak of Mt. Maurice in groups in a whitish yellow marble and in a glutinous earth; between Alfeld and Embach; in Hesse on that part of the Cnoreberg hill which is near the mountain where the fortified city of Spangenberg is located.23
Some stones found in the fields may have prominent lines and striae and the ignorant believe that these fall when it thunders. For this reason the Greeks call them brontia. They resemble the head of a tortoise. If they fall when it rains they are called ombria. Ours are light yellow, green, red, yel­lowish red and even with variegated colors. When polished they will reflect an image like a mirror. They are almost always in the form of a hemi­sphere, rarely oblong, sometimes the size of an egg but usually smaller. Some have two circles which appear to be units of measure. Five promi-
These minerals are fossil crinoid stems.
Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica Page of 251 Book V about lodestone, hematite, geodes, hematite, selenite, lapis secularum, asbestos, mica
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