Maryborough, a new H5 meteorite find from Victoria, Australia

Abstract

The Maryborough meteorite is a new H5 ordinary chondrite discovered about 2 km south of Maryborough, Victoria, in May 2015. It is a single stone measuring approximately 39 × 14 × 14 cm and with a mass of 17 kg. Plentiful indistinct chondrules are up to 1 mm across in a strongly recrystallised plagioclase-bearing matrix. Olivine and orthopyroxene in both the matrix and chondrules are uniform in composition (Fo_80.1Fa_19.3Te_0.5Ca-ol_0.04 and En_81.5Fs_17.1Wo_1.5 respectively).The main metallic phases present are kamacite, taenite and tetrataenite, often forming composite grains with troilite. There is no evidence for any shock-inducing event and the meteorite shows incipient weathering in the form of thin iron-oxide mantles around the Fe–Ni grains. A terrestrial age of less than 1000 years is estimated from C14 dating. While there are a number of historic reported meteor sightings in the Maryborough district, none can be tied to the meteorite’s find site. To date, Maryborough is the third H5 ordinary chondrite and the second largest single chondritic mass, after Kulnine (55 kg), found in Victoria.