摘要
Geological and geochemical features of tin-bearing magnetite-skarns are reviewed in this paper together with the author's opinion with respect to the mechanism of transportation of tin in this environment. In addition to cassiterite, the commonest mode of occurrence of tin in nature, three other occurrences are also of interest in tin-bearing magnetite-skarns: (1) Tin is present in extremely fine eassiterite as exsolution colloform in magnetite; (2) Being Found in some tin-bearing minerals such as malayaite,stokesite,nordenskioldine,Snpaigeite,Sn-lundwigite and hulsite in a variety of skarns;(3)Occurring in a numbor of skarn minerals such as garnet,pyroxene,spinel,amphibole,epidote,wollastonite and axinite,which become tinrich as a results of the substitution of Sn^4+ for Fe^3+ or Ti^4+ rather than for Fe^2+,Ca^2+ or Si^4+,When Mg^2+-,Fe^2+-bearing minerals and in some eases even sulfides or other mineralizer-containing minerals replace tin-bearing,Fe^3+-,Ti^4+-skarn minerals during the late stages of skarn alteration,tin in the pre-exsiting silicates may be extracted and remobilized thus contributing to the formation of the associated tindeposits.
Geological and geochemical features of tin-bearing magnetite-skarns are reviewed in this paper together with the author's opinion with respect to the mechanism of transportation of tin in this environment.In addition to cassiterite, the commonest mode of occurrence of tin in nature, three other occurrences are also of interest in tin-bearing magnetite-skarns: (1) Tin is present in extremely fine cassiterite as exsolution colloform in magnetite; (2) Being found in some tin-bearing minerals such as malayaite, stokesite, nordenskioldinet Sn-paigeite, Sn-ludwigite and hulsite in a variety of skarns; (3) Occurring in a number of skarn minerals such as garnet, pyroxene, spinel, amphibole, epidote, wollastonite and axinite, which become tinrich as a result of the substitution of Sn4+ for Fe3+ or Ti4+ rather than for Pe2+, Ca2+ or Si4+.When Mg2+ -, Fe2+- bearing minerals and in some cases even sulfides or other mineralizer-containing minerals replace tin-bearing, Fe3+ -, Ti4+ - skarn minerals during the late stages of skarn alteration, tin in the pre-exsiting silicates may be extracted and remobilized, thus contributing to the formation of the associated tin deposits.
出处
《地球化学》
CAS
1982年第3期301-309,共9页
Geochimica
