Spinelli Quarry (Part II) A 5-Year Field Investigation

摘要

Based on descriptions by Cameron et al (1954) and Stugard (1958), plus recent observations, it has simple internal zoning and mineralogy: a coarse-grained intermediate zone comprising most of the pegmatite and containing albite, microcline perthite and quartz with accessory muscovite and minor garnet and magnetite; a finer-grained border zone up to about 10 cm thick; and a quartz core zone. At the western end, only the border and intermediate zones are present, but magnetite is absent. Instead samarskite and columbite, typically in parallel growth with each other, are common accessories there, with very rare monazite. Their distribution appears to be scattered within the intermediate zone (see cross-section and photos of the pegmatite). Virtually all crystals are frozen in matrix as there are no significant miarolitic cavities in this pegmatite.