Page:Theophrastus - History of Stones - Hill (1774).djvu/47

 ; and the Mas formed of the whole appeared a Flint, or Pebble, of regular and imilar Subtance: and if, latly, this Matter, before its Application, had received other various-coloured Affluxes into it, they are een in the Concrete, in irregular Lines and Striæ, and it becomes an Agate, or other uch Stone. In all thee Caes the Matter firt formed into a Mas, yet remains in Form of a central Nucleus, in or near the Middle of the Stone, according to the equal or irregular Quantity of the'additional Matter which formed each Crut; this being ometimes all of the ame Colour with that Nucleus, remains unperceivable, but ometimes, as before oberved, being of different Colours, is evident to the Eye.

This Nucleus in ome, indeed mot of thee Maes, being of the ame Texture with the ret, has remained in its Place, and become a viible Spot of equal Hardnes and Beauty with the ret of the Stone: in others, after the Application of ome, or all the outer Cruts, it has hrunk into a maller Compas, detached itelf from the inner Crut, and become a looe, eparate Stone, rolling about in the Cavity, now too large for it; and rattling in it when haken. This is our Ætites; and the central Nucleus o detached, and hrunk, is its Callimus. In others, this central Nucleus has crumbled into looe, andy, or earthy Matter, and remaining in that Form, looe in its Cavity, has made what is called the Geodes, or batard Eagle Stone. The Geodes, and the Eagle Stone, o much renowned for Virtues, and o fabulouly talked of as to their Origin, are therefore no other than common Pebbles, the central Nuclei of which have, from the different Nature and Texture of the Matter of which they were formed, detached themelves from the uperadded Cruts, and either hrunk, on becoming more dry, into maller Dimenions; or fallen into the original Grit, or andy Matter, of which they were firt compoed. on; others may be haped by the Turner's Tools; others may be cut or awed: Some alo there are which no Iron Intruments will touch; and others which are very difficultly, or carce at all to be cut by them.