宁强碳质球粒陨石的岩石、矿物特征研究

宁强碳质球粒陨石的结构复杂,有粒状、斑状和炉条状等结构。球粒分为玻璃质和晶质两种。聚合体含量丰富、形态各异,有钢性和塑性两种聚合体。目前已查明的矿物有20余种,主要是镁橄榄石、贵橄榄石、烦火辉石、普通辉石和黄长石类矿物等。在宁强陨石中出现罕见的方解石、白云石。不透明矿物有陨硫铁、铁纹石—镍纹石、镍铁矿、磁铁矿和非晶质碳质。Fe/SiO_2为0.71—0.72,SiO_2/MgO为1.37—1.40。根据化学及矿物特征,该陨石应属C_2群。

Study on Mineralogical and Petrographic Characteristics of Carbonaceous Chondrite in the Ningqiang Area

Four. chondrites fell in the Ningqiang county,Shanxi province (i. e.Long- titude 105º54 E, Latitude 32º55´N) at 7:00 P.M.of 25 June 1983. About 46068 specimens have been collected. The exterior ofchondrite is a layer of fusion crust, approxrmazery 0.7-1 mm thick. In the interior of chondrite, white gray chondrules and aggregate irregularly disperse through the black matrix, and light yellow troilite and silver gray Awaruite and iron-nickel liamalite are observed. The morphologies of chondrite are circular, elliptic and irregular. According to the crystalline degree, they are glassy, cryptocrystalline, microcrystalline and various porphyritic, grained chondiite texture. The forms of aggregate are more complex. But, they are largely elliptical, irregular and myrmekitic texture. There are more than 30 types in Mineral . compositions.. Transparent miner- als have been found as follows: eorsterite, chrysolite, enstatite, augite, gehlenite, akermanite,spinel, apatite,monetite, .calcite, dolomite, quartz, bytownite and albite. Opaque minerals have been found as follows: troilite, iron-nickel kamalite, pentlandite, magnetite, awaruite, chromite, and uncrystallized carbon. Chemical composition(%): SiO2 33.95 Al2O3 2.74 TiO2 0.134 CaO 2.25 MgO 24.5 NaO 0.55 MnO 0.20 P2O5 0.25 Cr2O3 0.53 Ni 0.95 Co 0.070 Cu 0.032 Zn 0.010 C 0.401 NiS 0.94 (total 99.718) Main chemical parameters; Fe/SiO2 0.72 SiO2/MgO 1.39 The above characteristics show that these chondrites should belong to C3 typc.