Science. 1976 Nov 12;194(4266):724-5. doi: 10.1126/science.194.4266.724.
Spherical particles of silicate composition occur on the surface of some shatter cones from the collar rocks around the Vredefort structure, South Africa. They are best developed on shatter cones from a shale horizon but are also found on more arenaceous rocks and banded ironstones. They have not been found on shatter cones from the purer quartzites.
南非弗里德堡结构周围的颈圈岩石中，有些碎锥的表面上存在着硅酸盐组成的球形颗粒。这些颗粒在页岩层位的碎锥上发育最好，但也存在于更砂质的岩石和条带状铁矿中。在更纯净的石英岩形成的碎锥上则没有发现这些颗粒。
