Notable vein deposits exist in many regions of the Alps; placer deposits are common in Minas Gerais and Bahia, Braz.
The mining of alluvial deposits and, later, lode or vein deposits required crushing prior to gold extraction, and this consumed immense amounts of manpower.
Sphalerite also is distributed worldwide as an ore mineral in hydrothermal vein deposits, in contact metamorphic zones, and in high-temperature replacement deposits.
It occurs as an accessory mineral in igneous rocks, in vein deposits with quartz and sulfide minerals, and in sedimentary rocks, such as shale, coal, and limestone.
In the 18th and much of the 19th centuries, the very large vein deposits of Cornwall were the major source of tin.
Vein deposits, such as those in Bolivia and the United Kingdom, usually occur in granite formations and are recovered by conventional underground hard-rock mining techniques.
The mineral deposits in these districts are closely related to volcanic and subvolcanic rocks, and represent mainly porphyry and epithermal vein deposits, which formed within short periods of time in each district.
It typically occurs in ore veins deposited at medium and high temperatures, as in Río Tinto, Spain; Ani, Japan Butte, Mont .; and Joplin, Mo.
No anomalous sites were observed for these metals and their background concentrations indicate sulphide mineralization related to vein gold deposits.
