3584 SECTIONAL TRANSACTIONS.—C. 
sulphide-material introduced, and, as a result, vug and fissure minerals of remarkable 
composition formed. Minerals of at least three periods, though only some as relicts, 
are, therefore, present on this deposit. 
Another occurrence shewing a great variety of minerals is the zinc-manganese 
ore deposit of Franklin Furnace, New Jersey. About 100 different minerals have 
been quoted, including franklinite, willemite, zinkite and a great number of rarer 
species such as tephroite, schefferite, gahnite, polydelphite, etc. Perhaps sphalerite, 
pyrite and rhodochrosite are the original minerals which, after a phase of oxydation, 
underwent a metamorphic process, possibly due to pegmatites. 
Of exceptional complexity, again, is the sulphosalt deposit of Lengenbach 
(Binnental). A series of sulphosalts, including Hutchinsonite, Binnite, Seligmannite, 
. Skleroklas, Lengenbachnite, Rathite, were first described from this locality. There 
is no doubt that alpine dislocation-metamorphism of the pennine type is responsible 
for the formation of the sulphosalts. The original deposit was of a perfectly normal 
type. 
In view of the fact that a large number of rock-forming minerals such as grammatite, 
actinolite, vesuvianite, grossularite, sillimanite, cyanite, staurolite, chlorite, serpentine, 
talc, epidote, zoisite, sericite, etc., etc., are practically restricted to metamorphic 
rocks, it is not surprising that the number of minerals peculiar to metamorphic ore 
deposits should be considerable, even though the occurrences are comparatively rare. 
Some deposits which shew no great particularities as regards mineral composition 
have, nevertheless, been variously interpreted in respect to questions of genesis. No 
doubt primary traits have in many cases been obliterated by redistribution of matter. 
An example is offered by the Witwatersrand gold deposits, which in the opinion 
of the writer, are undoubtedly sedimentary placer deposits which have been subjected 
to epi-metamorphism accompanied by migration of matter. The vein-like develop- 
ment of the ore recalls the torsion-fissures of alpine type, and is not a result of magmatic 
action. Metamorphism has converted siderite and greenalite rocks of the Marquette 
and the east Mesabi district to magnetite-griinerite schists and to specularite deposits. 
Some fahIband deposits have been recrystallised during a period of rock metamorphism. 
According to Schneiderhéhn the peculiarities of the copper area of Northern Rhodesia 
may be ascribed to metamorphism. In such areas it is particularly interesting to 
reconstruct the processes of migration carried out by the solutions as they offer the 
best insight into the exchanges and replacements of material which take place during 
periods of rock metamorphism. 
From the standpoint of structures and textures, exceptionally interesting conditions 
are found in the veins of the ore deposits which accompany the quartz, adularia 
zeolite veins of alpine type and have been subjected to dislocation metamorphism. 
Swiss occurrences have recently been described by Koenigsberger, Friedlander and 
Huttenlocher, those of Rammelsberg and Meggen (Germany) by Frebold and Ramdohr, 
and examples from the United States and British Columbia by Emmons, Lindgren, 
Uglow, etc. Many such deposits are to be found in Scandinavia, and possibly the 
pyrite deposits of Rio Tinto and other similar occurrences should be included in this 
type. Insome cases the mode of formation was sedimentary, in others of the combined 
sedimentary-volcanic type. In certain instances, again, a distinctly hydrothermal 
veinlike development can be observed. Dislocation metamorphism has produced 
similarly-directed alterations at the various localities so that the resulting products 
converge to form a new type. 
All the fundamental phenomena of rock metamorphism as, for example, clastic, 
blastic and plastic changes, mechanical deformation, recrystallisations, etc., must be 
taken into account in order satisfactorily to explain the details of such deposits. 
Of technical importance is the tendency to form compact, very finely-granular 
granoblastic or diablastic aggregates—such as ‘ Bleischweif’ and the so-called 
‘ Misch-’ and ‘ Meliererze.’ The fine- grained intergrowth of the different minerals 
causes difficulties in the metallurgical treatment of the ore. Banded layers of 
galena or such which shew the effects of gneissose lamination have suffered mainly 
plastic deformation accompanied by the formation of strain centres and the bending 
of glide lamellae. Recrystallisation has converted such material into the compact 
diablastic or granoblastic ore. The process of recrystallisation has been aided, as in 
all natural mineral aggregates, by solution, although in the case of relatively soft 
metallic ores, recrystallisation without the aid of sclvents also occurs. Whereas 
plastic deformationis not very frequent with silicates, certain ore minerals such as galena, 
and, to a certain extent, zincblende, shew properties approaching those of the most 
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