A great Crystalline TALK-SPAR. So I call it. Sent by Dr. Erasmus Bartholine, together with a large account of it, published in a the Phil. Transactions. (a) (a) Num. 67. And by the Dr. (b) (b) Experimenta Crystalli Islandici Dis-Diaclastici. himself in a distinct Treatise. 'Tis a foot long, ½ a foot broad, and two inches and ½ thick. Of a Rhomboid Figure, and the narrow sides likewise sloaped, as in the Crystals of Talk. It breaketh also into parts of the same Figure, or near it. Yet not flexible, but brittle. Polite, colourless, and transparent, as the clearest Chrystal. Yet soft and dissoluble especially with Nitrous Spirits; and by a strong fire reduceable to a Calx. Of a very different nature from Crystal, although the said Dr. is pleased so to call it. When heated, it is of an Electrick Nature, or like Amber taketh up straws and other light Bodies. That which he principally Notes is, That the Objects seen through it, in certain positions, appear sometimes single, sometimes double, and sometimes sixfold. Which he ascribes to a Refraction peculiar to this Stone. And to me, it seems probable, That this various Refraction depends upon the structure of the Stone, sc. as it is not one piece absolutely entire, but composed of several Plates; and those not all in a like manner, but differently contiguous; so, as in some places, several Plates may make but one Refraction; in others, two or more. It was dug out of a very high Mountain in Island, one whole side whereof consisteth of this Spar.