Vein deposits

Vein Deposits. The vein deposits of uranium are those in which uranium minerals fill cavities such as cracks, fissures, pore spaces, breccias, and stockworks. The dimensions of the openings have a wide range, from the narrow pitchblende-fiHed cracks, faults, and fissures in some of the ore bodies in Europe, Canada, and AustraHa to the massive veins of pitchblende at Jachymov, Czech RepubHc (15). 

The chemical compositions of opaque minerals (sphalerite, electrum) are different in two types of deposits. The FeS content of sphalerite from vein deposits of the Te-type is generally lower than that of the Se-type (Fig. 1.118). However, FeS content of sphalerite from massive deposits of the Te-type (Kobetsuzawa, Suzaki) is high, ranging from 1 to 7 mol%. The Ag content of electrum from the Se-type is higher than that from the Te-type (Fig. 1.119). 

Therefore, the wider time range from middle Miocene to present is considered below based on available age data on hydrothermal ore deposits (Kuroko deposits, epithermal vein deposits) and hydrothermal alteration in the mine areas in Northeast Japan. 

Figure 1.186. Frequency (number of analyses) histogram of Ag content (atomic %) of auriferous vein and gold-silver vein deposits in Japan. Frequency means numbers of analyses (Shikazono and Shimizu, 1987).

Aq- (Fig. 1.189), while an increase in pH causes a decrease in wrAucr/ Au(Hsr It is apparent in Fig. 1.190 that Au bisulfide species are more abundant than Au cliloride species under the conditions common for ore fluids responsible for Japanese Au-Ag veins. However, Au chloride species may dominate Au bisulfide species in ore fluids responsible for the gold-quartz (auriferous) vein deposits, as shown in Fig. 1.189. 

Figure 1.189. The relationship between tAuCl / Au(HS)" temperature. Hatched and dotted areas represent the probable geochemical environment for typical Japanese gold-silver vein and auriferous vein deposits, respectively. A, mci- = 10, mK+ =2, qh2S = 10, K-feldspar/K-mica/quartz equilibrium B, mQ- = 1. niK+ =0.2, H2S = 10 - , K-feldspar/K-mica/quartz equilibrium C, mci- — 1, Wk+ =0.2, qh2S = 10, K-feldspar/K-mica/quartz equilibrium D, mci- =0.2, mK+ =0.04, oh2S = 10 , K-feldspar/K-mica/quartz equilibrium E, mci- =0.2, m <+ =0.04, uh s = 10 K-feldspar/K-mica/quartz equilibrium F, mci- =0.2, = 0.04, UHiS = 10 , K-feldspar/K-mica/quartz equilibrium. Thermochemical data for the calculations were taken from Helgeson (1969), Seward (1973), Drummond (1981), and Henley et al. (1984). (Shikazono and Shimizu, 1987).

Horikoshi, E. (1975b) Statistical distribution of strikes of the Neogene vein deposits in the NE Japan arc. In Horikoshi, E. (ed.). Island Arcs, Marginal Seas, and Kuroko Deposits. Mining Geology Special Issue, 11, 117-124 (in Japanese). 

Ishihara, S., Sakamaki, Y., Sasaki, A., Teraoka, Y. and Terashima, S. (1986) Role of the basement in the genesis of the Hishikari gold-quartz vein deposit, southern Kyushu. Japan. Mining Geology, 36, 495-510. 

Nagayama, T. (1992) The precipitation sequence of the Hishikari vein deposits, Kyushu, Japan. Unpub. Masters Thesis, U. Tokyo. 

Nagayama, T. (1993b) Pressure loss, boiling and vein formation An example model for the mineral precipitation in the Hishikari vein deposits. Resource Geology Special Issue, 14, 29-36. 

Shikazono, N. and Shimizu, M. (1987) The Ag/Au ratio of native gold and electrum and the geochemical environment of gold vein deposits in Japan. Mineralium Deposita, 22, 309-314. 

Smith, D.M. Jr., Albinson, T. and Sawkins, F.T. (1982) Geologic and fluid inclusion studies of the Tayoltita silver-gold vein deposits, Durango, Mexico. Econ. Geol, 77, 1120-1145. 

Hydrothermal vein deposits result from hydrothermal solutions. Hydrothermal solutions are essentially the residual hot solutions remaining after magmatic crystallisation (juvenile... 

The physical concentration is primarily used in beneficiation of alluvial and some coarser grained vein deposits. The combination of gravity and flotation is normally used for beneficiation of hard rock ores. 

The Brunswick Subduction Complex (BSC) is best know as the host sequence to world class, syngenetic volcanogenic massive sulfide deposits of the Bathurst Mining Camp (BMC) hosting deposits such as the giant Brunswick No. 12 VMS deposit (>300 Mt of massive sulfides). Less well known are the syntectonic, precious-metal breccia and (or) vein deposits/occurrences in the BSC. The shear zone-hosted Middle River gold deposit (MRG) is the most significant of these and has returned assays of up to 7.44 g/t Au over 6.5 m (DDH MR-05-06). 

Lesser but in some cases significant amounts of rhenium are present in other types of deposits such as skarn deposits (e.g., Needle Mountain-Gaspe Copper), pegmatite-aplite deposits (e.g., Pidgeon Moly) and vein deposits (e.g., Playter, Golconda). 

Although porphyry Cu and Cu-Au deposits are likely the most important potential source of rhenium in Canada, other types of deposits including sediment-hosted Cu deposits and some vein deposits also represent potential sources. 

Fluorine for industrial use is almost exclusively obtained from fluorite. There are many possible fluorite-ore types. It occurs as fissure-fill and manto-replaced types, and in pegmatites, residual/eluvial deposits, carbonates and phosphate deposits. It is a gangue mineral in many base metal deposits, but due to stringent trace metal requirements often can t be economically beneficiated to a saleable product. Most fluorite ores are selectively mined, and ore from some minor vein deposits is then upgraded to a saleable product by sorting. 

A similar tendency is observed between vein and country rock of vein deposits in country rocks, p3U ite generally takes cubic Tracht. This tendency is recognized in many observations on t3q>omorphism reported in the former Soviet countries [2]. 

ALABANDITE. Manganese sulfide. MnS. Associated with pyrite, sphalerite. and galena in metallic sulfide vein deposits. 

Vein deposits 10,000-30,000 Canada (near Great Bear Lake in the Northwest Tenitoiy) Western United States France Germany Russia Africa Australia China... 

Vein deposits (pegmatites, unconformity deposits) 2,000-10,000 Canada (Saskatchewan) Russia. Australia... 

---