534 SYSTEMATIC DESCRIPTION OF PRECIOUS STONES 



is due to the fibrous structure of the mineral. Stones of this description are cut with a 

 shghtly convex surface, and are set in brooches, bracelets, medallions, &c., as well as in 

 rings. The material is sometimes used for beads, which are strung together and worn as 

 necklaces or bracelets. Not infrequently such beads are chatoyant, and when this is the 

 case they resemble black pearls in colour and lustre. Small cubes of haematite are mounted 

 as pins. Generally speaking, however, the mineral has a very limited application as an 

 ornamental material, for example, in mourning jewellery, and is very low in price. 



Hematite has been used as an ornamental stone from the very earliest times. 

 Numerous cylinder-seals, some of them engraved, have been found in the ruins of Babylon, 

 and ornamental objects of the same material are found in the ancient Egyptian tombs. 

 In classical times haematite was extensively used for intaglios and for other similar purposes, 

 being a stone of fine appearance and easy to work. 



The fine powder of haematite is much used as a polishing material in the working of 

 precious stones, especially some of the softer kinds, although another material is available 

 and is also used for this purpose, namely, the artificially prepared oxide of iron known as 

 jewellers'" rouge. The massive fibrous variety of haematite, which is cut as an ornamental 

 stone, constitutes the material of which polishing tools for burnishing gold and silver 

 jewellery are made. The city of Santiago de Compostela is stated to supply almost the 

 whole of the world with these tools. 



ILMENITE. 



Ilmenite is very similar to haematite in appearance and is sometimes used for 

 ornamental purposes. The chief difference between the two minerals lies in the fact that 

 ilmenite contains titanium dioxide as well as iron oxide. A variety of ilmenite known as 

 iserine occurs as black, rounded grains in association with sapphire in the sands of the 

 Iserwiese in Bohemia. Except for the absence of a fibrous structure, ilmenite possesses 

 essentially the same characters as haematite, but is susceptible of a higher degree of polish ; 

 it is distinguished from haematite by the fact that its streak is black instead of red, and 

 that it is occasionally magnetic, which is never the case with hasmatite. The application 

 of the mineral as an ornamental stone is so limited that further consideration is for the 

 present purpose unnecessary, but it may be mentioned in conclusion that an effective 

 ornamental stone occurs at Cumberland, in Rhode Island, U.S.A., which is composed of 

 grains of white quartz embedded in black ilmenite. 



RUTILE. 



Rutile is a mineral which consists of titanium dioxide (TiOg), and is frequently found 

 as crystals belonging to the tetragonal system. It ranges in colour from red through 

 brown to black, and possesses a strong metallic to adamantine lustre. Some specimens are 

 sufficiently beautiful to be cut as gems, and may then be mistaken at a first glance for 

 black diamond, from which the stone is distinguished, however, by its lower degree of 

 hardness (H = 7-J), its greater density (sp. gr. = 4-2 — 4!'3), and, in transparent specimens, 

 by the strong double refraction and marked dichroism. Rutile is of common occurrence, but 

 does not, as a rule, possess the characters essential for a gem ; it is, therefore, only rarely cut. 



