The deposits of the useful minerals & rocks; their origin, form, and content . dosu, Ingustosa, Gennamari, etc. A point worthy ofnotice is that this lode contains but very little sphalerite. To the southof this granite another lode-system occurs, the members of which strikesouth-east to east-south-east. As will be seen from Fig. 349, these twosystems form together a surround to the granite. In the neighbourhoodof Iglesias are found the lead lodes of San Giovanni to the south, and SanBenedetto and Malacalzetta to the north ; while to the west the importantmetasomatic deposits worked in the Nebi
The deposits of the useful minerals & rocks; their origin, form, and content . dosu, Ingustosa, Gennamari, etc. A point worthy ofnotice is that this lode contains but very little sphalerite. To the southof this granite another lode-system occurs, the members of which strikesouth-east to east-south-east. As will be seen from Fig. 349, these twosystems form together a surround to the granite. In the neighbourhoodof Iglesias are found the lead lodes of San Giovanni to the south, and SanBenedetto and Malacalzetta to the north ; while to the west the importantmetasomatic deposits worked in the Nebida and Monteponi mines , there is the no less important zone of oxidized zinc deposits atMalfidano to the north-west of Iglesias. The lode-series at Montevecchio includes three lodes striking east-westand dipping 65° to the north. Of these the most important, having awidth of 60 m., stands out on the surface from the slaty comitry-rock hkea massive quartz wall. The galena, which may contain as much as 80 THE METASOMATIC LEAD-SILVEK-ZINC DEPOSITS 751 PorttMcldu. Ca/oOornesfic Cana/grancfePan c/i Zt/chero ^ Porto Cotallo WMorfxj ° wm ^ 23 E3 S EZII Quater- Eocene. Trias. Phyllite. Oie- Silur. Silur. Cambr. Granite. Por- Lodes. Oxidized nary. bearing gran- limestone, sand- pbyry zinc lime- waeke stone dykes. , and slate. and slate. Fig. 349.—Geologicfil map of the mining district in Sardinia. Scale, 1 : 240, Joppi, Lambert, and Deferrari. per cent of lead and 800 grm. of silver per ton, occurs in lenses sometimes 752 OEE-DEPOSITS as much as 8 m. in wndth. In depth sphalerite becomes more production amounts to over 10,000 tons per year. The lode worked in the San Giovanni mine lies almost oppositeto Monteponi in a valley descending from Iglesias to the sea. TheSilurian slate and the Devonian limestone have here an almost verticaleast-west contact, along which runs a lode. The main lode howeveroccurs between a red dolom
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectminesandmineralresou
