Note 2725 — BOOK XXXVI. THE NATURAL HISTORY OF STONES. (continued 2)
John Bostock translation
The colour of Specular iron, or red peroxide of iron, being of a dark steel-grey or iron-black, this is probably another variety of it. Ajasson thinks that it includes compact or massive red oxide of iron, and scaly red iron, or red iron froth, which leaves red marks upon the fingers.