CHAPTER XVII 
ORE-FORMATIONS—continued 

Bedded Veins or Quasi-bedded Ore-Formations. Irregular Ore-Forma- 
tions—Masses occupying Cavities; Metasomatic Replacement ; 
Impregnations ; Disseminations ; Contact Ore-Formations. Origin 
of Ore-Formations — Magmatic Segregation Ores; Magmatic 
Extraction Ores; Secretionary Ores; Sedimentary Ores ; Theories 
of Lateral Secretion and Ascension. 
2. BEDDED VEINS OR QUASI-BEDDED ORE-FORMATIONS 
WHEN sheets of ore occur apparently interbedded amongst 
more or less metamorphosed sedimentary rocks or schists, 
into which they send veins and threads, they may be termed 
bedded veins or quasi-bedded ore-formations. These forma- 
tions are not to be confounded with the /fats which are 
associated with “masses” (p. 259), and not infrequently also 
with lodes (p. 252), for they are not connected with true 
fissure-veins or lodes. Their origin is obscure. Not infre- 
quently they seem to occupy planes of weakness or cavities, 
produced during the process of folding and metamorphism— 
for the rocks among which they occur usually dip at high 
angles and are more or less altered. The veinstone in some 
cases is commonly quartz which often carries gold and various 
metallic sulphides. While bedded veins of this kind are not 
infrequently of considerable width, and may simulate the 
persistence of true lodes, both as regards lateral and vertical 
extension, they are usually more or less lenticular and inter- 
rupted. A good example is furnished by the “saddle-reefs ” 
of Bendigo Goldfield (Victoria, Australia) (see Fig. 102). 
The country-rock at this place consists of slaty-shales and 
altered sandstones, disposed in a series of steep anticlines and 
synclines. The abrupt plication of the rocks has caused 
255 
