【摘要】 <正>一、弓长岭石榴石的成因弓长岭二矿区的含铁建造为太古代硅铁建造而非碳酸盐建造,故有利于形成非钙榴石,而不利于形成钙榴石.该矿区条带型贫铁矿类型有磁铁石英岩、赤铁石英岩、阳起石磁铁石英岩、绿帘石磁铁石英岩、普通角闪石磁铁石英岩;隐纹型富铁矿类型有石英磁铁矿、镁铁闪石磁铁矿、绿泥石磁铁矿、石墨磁铁矿.贫矿含TFe27～39%,SiO₂32～48%;富矿含TFe54.72～67.91%,SiO₂2.28～21.58%.两者均有较多的硅铁,有利于形成铁铝榴石.但硅铁矿体中缺铝,故铁铝榴石又较少见.此类硅铁矿体变质前原为胶体沉淀,故当围岩中更多还原

【Abstract】 Some almandites from Gongchangling, China show that their change of crystal forms from a{110} to n {211} is marked by the increase of andradite component and decrease of pyrope and almandite components in the garnet, resulting in the change of TFe, G, a0, V0 and VHN.Their infrared spectra confirm that they are iron-rich almandites with their L band frequencies which equal to 315-318cm-1 and their K-L band frequency differences which equal to 23-25 cm-1 The increase of andradite component decreases the L band frequency and increases the K-L band frequency difference.The MO8 and MO6 polyhedra are found to play the main role respectively in the vibrations of the low and medium frequency regions, as is further proved by regression analysis.Their Mossbauer spectra show that they are high-spin iron minerals rich in ferrous iron with chemical shiff which equals to 1.25-1.28 cm/sec, and quadrupole splitting which equal to 3.47-3.51 mm/sec.The increase of ferrous iron decreases the quadrupole splitting while the introduction of ferric iron decreases the chemical shift. The higher the symmetry of the ferrous minerals and its composing polyhedra,the less will be their quadrupole splitting.There is a good agreement between the mode of occurrence of our garnets and the result given by the Mossbauer spectra. Both IRS and Mossbauer spectra may be applied to the identification of pyralspite garnets of the porope-almandite series.The {211} crystals and their growth pyramids are higher in CaO content than {110} crystals and their growth pyramids as a whole and even in the center of the crystal or at the terminal of the growth pyramids, as is proved by the electronic microprobe analysis. Furthermore, it is proved that our d{110} almandite metacrysts are not the dehydrated products of chlorite during thermal metarnorphism.pt. 2-4 & 7, 8 of this paper had been accepted by the poster session of the 12 th General Meeting of IMA-80(1), supplement are made after the MeetingTheir spectroscopic study leads to the conclusion that their material is volcano-sedimentary in origin and is closely connected with the orthometamor-phic amphibolites in the BIF.The investigation of their distorted forms lengthened along L3 and L4 shows that the distortion is caused by the faulting stress during crystallization.The almandite component in the almandites may be used as an indicator for prospecting of iron ores with different grades. The andradite component in the almandites may be used as an indicator for prospecting of pyrite ore and hematite ore other than magnetite ores.更多还原