SCIENCE- GOSSIP. 



269 



geranii was swept in abundance from wild 

 geranium. The other tenants of the sweep-net 

 included Linwnius eylindrieus, Corymbites quercus, 

 Apion ervi, Stenus pallitarsis, Luperus flavipes, 

 and Lema melanopa. Melasoma aeneumi was 

 plentiful on alder. Elmis aeneus occured in plenty 

 among moss (Hypniivt palustre) growing on stones 

 submerged in the river. Anthobium sorbi was in 

 thousands on hemlock. An afternoon at Orton in 

 the middle of June produced some good things, 

 including Asemum striatum and Pissodes pint 

 from fir logs. A small pond contained Agdbns 

 bipustulatus, A. cltaleonotus, and Hydroporus mem- 

 nonius. Many species of beetles were found by 

 beating. From sallow came Ellesehus bipwietatus, 

 Cryptorhyncltus lapathi, RhyncMtes minutus, etc. 

 From birch, Rhynchites betulae and Luperus 

 rufipes. Rhamphus flavicornis was obtained com- 

 monly this year by general beating. In the Orton 

 district later in the year I found a single specimen 

 each of Treclius secalis and Amara spinipes, both 

 under stones, and by sweeping, Mantura obtusata. 



In another visit to Geltsdale at the end of July 

 I was fortunate in taking Paehyta octomaculata 

 from hemlock, and in the quarry Clivina collaris. 

 Bembidium paludosum was fairly common on a 

 sandy stretch by the river. In the Newbiggin 

 Woods by the river side I found Bonacia linearis 

 in abundance on iris, many specimens having a 

 fine purple gloss, which, however, almost dis- 

 appeared after death. During the late autumn I 

 was unable to do much collecting, but on Novem- 

 ber 2nd, 1901, at Durdar, with Mr. F. H. Day, we 

 each took a single specimen of Euryporus pieipes 

 from Sphagnum, these being, perhaps, the gems of 

 a fairly successful season's collecting. 

 11 Close Street, Carlisle. 



MANGANESE ORES OF 

 THURINOIA. 



By C. Boulenger. 



T~\URING a stay in Thuringia last autumn I 

 -*-^ had the opportunity of visiting the manga- 

 nese mines of Ilmenau aud its neighbourhood. 

 Although now practically exhausted these miaes 

 were extensively worked some ten years ago, and 

 this district was placed among the most important 

 manganese centres of Europe. The cessation of 

 activity is, however, not entirely due to exhaustion 

 of the yielding powers of the mines, but also to 

 the increased price of labour and the large im- 

 portation of cheaper though inferior ores from 

 America and elsewhere. From a commercial point 

 of view, the chief ores are pyrolusite and psilo- 

 melane, both of which occur at Oehrenstock, near 

 Ilmenau, as well as on the Rurnpels and Mittel moun- 

 tains near Elgersburg. At the former locality two 

 mines only are still worked ; yet the numerous waste- 

 heaps, a striking feature of the plateau upon which 



the village is situated, testify to the extensive 

 mining operations carried on in former years. 



Pyrolusite, termed by the German miners 

 " Weichbvaunstein," is the more important of the 

 above-mentioned ores on account of its great 

 purity, and of the almost total absence of silica 

 and oxides of iron. That extracted from the 

 Gottesgabe mine at Oehrenstock contains about 

 97 per cent, of pure manganese dioxide and 2 per 

 cent, of water ; the remainder consists of various 

 impurities, such as lime, baryta, and occasionally 

 traces of silica. The ore occurs chiefly with 

 tabular heavy spar, and exceptionally with calcite 

 or fluorite in quartz porphyry. The breadth of the 

 lodes varies from a few inches, in which case the 

 porphyry mass is occasionally covered with a net- 

 work of fine veins, to ten or eleven feet. This, 

 however, is very exceptional. The strike of the 

 manganese lodes is from N.E. to S.W., the inclina- 

 tion is mostly 10°-25°. 



The pure ore is highly valued, the current price 

 during my stay being 35 . marks per cwt. Large 

 quantities are used by glass manufacturers for the 

 purpose of discharging the brown and green tints 

 in glass, due to oxides of iron. Hence the name 

 " pyrolusite." For a similar reason the manganese 

 compound is called by the French " le savon des 

 verriers." Extensive use of this mineral is also 

 made for electric batteries and for evolving 

 chlorine in the preparation of bleaching powder. 

 For the above purposes the pyrolusite is used with- 

 out any preparation. An alloy of iron and man- 

 ganese called " Spiegeleisen " is employed in the 

 Bessemer process for the manufacture of steel. 



Psilomelane occurs, likewise in quartz porphyry, 

 on the Lindenberg at Ilmenau and at Elgersburg ; 

 at the former locality together with violet fluorspar, 

 at the latter mostly without gang. This ore, 

 called by the miners " Hartbraunstein," is very 

 impure ; hence the composition is doubtful. Dana 

 calls it hydrous manganese manganate, and gives 

 the formula H 4 Mn0 5 . That from Ilmenau does not 

 contain much more than 70 per cent, of oxides of 

 manganese, the impurities consisting chiefly of 

 oxides of barium, calcium, magnesium, and a con- 

 siderable amount of silica. This greatly diminishes 

 the value of the ore, one hundredweight being 

 worth but a few marks. 



Of the other ores found in Thuringia haus- 

 mannite and braunite formerly occurred together, 

 though in small quantities, in the mines of Oehren- 

 stock. Specimens may still be obtained, by patient 

 search, on the waste-heaps of the exhausted mines 

 Dana, in his " System of Mineralogy," mentions 

 manganite as occurring with the other ores in the 

 porphyry of Ilmenau and Oehrenstock. I was, 

 however, unable to come across any specimens 

 during my stay, nor did I see any in the large 

 collections of manganese ores at Ilmenau. 

 8 Courtfield Road, 



South Kensington, S. W. 



