MINERALOGY OF THE PACULA METEORITE BY ELECTRON MICROPROBE ANALYSIS

Pacula is a rocky metorite that was observed to fall on 1881 in the State of Hidalgo, Microprobe mineral studies confirmed its classification as an ordinary chondrite, class L and type 6. Petrographic criteria that indicate a shock stage S4 include: the presence of chromite veins, mosaicism and undulose extinction in olivine, chromite-plagioclase associations, metallic copper, and troilite nodules. The principal constituent minerals are: olivine, pyroxene, feldspar, dissiminated iron-nickel metal (kamacite and taenite), troilite, chromite, and in minor amounts merrilite and whitlockite. Most silicates form extremely fractured crystalline masses. Fusion materials, particularly opaque phases, are common as pockets and veins. Chondrules are diffucult to distinguish because they appear integrated to the matrix, and their rims are rather diffuse. Feldspar is present in masses up to 2 mm in size and its composition corresponds approximately to oligoclase. Pyroxenes are enstatite and diopside orthopyroxene and Ca-rich pyroxenes.