冀北宣龙式鲕状铁矿分布很广,含矿层较厚,是有工业意又的沉积铁矿床。鲕粒成份以赤铁矿为主,其次为菱铁矿和鲕绿泥石,有时还含有鲕状石英及鲕状黄铁矿等。赤铁矿多分布在近地表处,往深部则菱铁矿增多。据此,一般人认为这是沉积相变关系,即由于海水深度不同而形成的氧化铁矿相及菱铁矿相,井预 North Shaanxi Xuan Long-style oolitic iron ore is widely distributed, thick ore-bearing layer, is an industrial-purpose deposits of iron deposits. Ooids are dominated by hematite, followed by siderite and algal chlorite, and sometimes oolitic quartz and oolite pyrite. Hematite and more distributed in the near surface, to the deepest siderite increased. Accordingly, most people think that this is the relationship between sedimentary facies, which is due to the different depth of seawater formed by the iron oxide and siderite siderite, well