192 ScienHfic Intelligence— 'Mineralogi/. 



Oxygen. 



Titanic acid, 59*00 23-43 



Lime, . . ... . . 36-76 10-16 



Protoxide of iron, with slight traces of 



protoxide of Manganese, . . . 4-79 1'09 



Magnesia 0-11 0-04 



100.66 



— Poijgendorff's Annalen, vol. Ixii. p. 598. 



18. PoJykrase and Malakone, two New Mineral Species. — In a 

 Memoir on the Norite of Hitteroe,* contained in the second part of 

 Kellhau's Gaea Norvegica, Scheerer describes, under the above names, 

 two new substances, detected by him in the granite veins which tra- 

 verse the norite. Both are generally associated with orthite, and are 

 often accompanied by Yttria-spar or phosphate of Yttria ; and they 

 are not unfrcquently to be observed mixed with the former. This 

 is probably the cause of small quantities of titanic acid and zirconia 

 being sometimes detected in the orthite of Hitteroe; for they un- 

 doubtedly do not belong to that mineral, but may have been derived 

 partly from the polykrase, and partly (the zirconia) from the mala- 

 kone. The polykrase (derived from <!rcikii and x.^aei;) is nearly re- 

 lated to the polymignite, but still differs from it in many respects. 

 Its crystals are sometimes 1 or l^- inches in length, and belong to 

 the rhombic system. The relations of the axes cannot, however, be 

 deduced from those of the polymignite. There is no indication of 

 cleavage, and the fracture is conchoidal. The hardness cannot be de- 

 termined with exactness, as the crystals are very easily frangible ; but 

 it appears to be less than that of the polymignite. The specific gravity 

 = 5-105. The colour is pure black, but thin splinters are translu- 

 cent, and have a yellowish-brown colour. The streak is greyish- 

 brown. The lustre is less considerable than that of polymignite. 

 A qualitative analysis of polyki-ase afforded the following consti- 

 tuents : — Titanic acid, Tantalic acid, Zii'conia, Yttria, Oxide of 

 Iron, Oxide of Uranium, Protoxide of Cerium, together with a small 

 quantity of Alumina, and traces of Lime, Magnesia, and perhaps an 

 Alkali. The constituents of polvmignite are, according to Berzelius, 

 Titanic acid (46-30), Zirconia (14-14), Oxide of Iron (12-20), 

 Lime (4-20), Protoxide of Manganese (2-70), Protoxide of Cerium 

 (5-0), Yttria (11-50.) We have, therefore, the following differ- 

 ences in the composition of the two minerals : — 1, The presence of 

 Tantalic acid and Oxide of Uranium in polykrase ; and, 2, the ab- 

 sence of Protoxide of Manganese, and the almost total absence of 

 Lime in that mineral. The malakone (from liaXaxoi) is so called 

 from its possessing an inferior degree of hardness to the zircon, a 

 mineral with which it has very considerable analogy. Its crystallo- 



* The Island of Hitteriie is also a locality of Gadolinite, and is situ- 

 ated on the south coast of Norway, about twenty-three English miles 

 to the north-west of Cape Lindesnas. 



