b'Space rocksFeaturerich inclusions (CAIs) that pre-date the formation of the solar system (Figure 6. They are derived from group C asteroids such as Bennu and Ryugu, which are currently being visited by the Osiris-REX and Hayabusa 2 spacecraft respectively (Laurette et al. 2019, Watanabe et al. 2019). Such asteroids are the most common in the asteroid belt but carbonaceous chondrites are rare because of their weak structure and easily weathered mineralogy. The class is represented in the GA display by the Murchison meteorite, which fell in Victoria in 1969.Achondrites: This class of meteorites lack chondrules and are composed of mafic or ultramafic rocks such as basalt, dolerite, gabbro, and pyroxenite. They thus represent material from differentiated bodies, such as rocky planets, the larger rocky satellites, and larger asteroids. Martian and lunar meteorites are examples of achondritic meteorites. At present GA only has a cast of an achondrite from the asteroid belt, the Millbillillie meteorite from Western Australia, plans exist to replace with an actual specimen in the future.Iron meteorites: Numerous small planets were formed in the early solar system. Their mantles and crusts were stripped by collision, exposing their iron-nickel alloy cores, these are preserved as the M group asteroids and the source of the iron (and perhaps some of the stony iron) meteorites. Psyche is one of the larger Figure 5.GA meteorite display. examples, and there are plans for it to be orbited by the Psyche mission in 2026. Iron meteorites are represented in the GA meteoroids and asteroids (Figure 6). All three have receivedcollection by Henbury, Coolac, Tawallah, and Mundrabilla, the some shock metamorphism, The Kybunga meteorite belongs tolast as a sawn slab. The Henbury meteorites are associated with a the L5 type (Meteorite Bulletin database 2019e), with sufficientcluster of small impact craters south of Alice Springs.metamorphism to homogenise olivine and pyroxene, convert allStony iron meteorites: This class of meteorites are among the low-Ca pyroxene to orthopyroxene, cause the growth of variousrarest known and are among the most beautiful. They are well secondary minerals, and blur chondrule outlines (Meteoriterepresented in the GA display by Imiliac (Chile), Brenham (US), Bulletin database 2019f). The Nine Mile and Allan Hillsand Huckitta (NT). They formed at the boundary between the specimens represent the slightly more metamorphosed L6 type.metallic cores of small planetary bodies and the silicate mantles.These have been metamorphosed under conditions sufficient to homogenise all mineral compositions, convert low-Ca pyroxene to orthopyroxene, coarsen secondary phases textures,Tektitesand obliterate many chondrule outlines, all without, however, melting the meteorite; no melting has occurred (MeteoriteTektites are glassy bodies generally widely accepted to Bulletin database 2019g). represent impact melt that was ejected during crater formation. Tektites are found in Europe, Africa and North Carbonaceous chondrites: These very primitive meteoritesAmerican, and have been linked to specific craters. The mostly are notable for their relatively high content of organicwidely distributed tektite field is the Australasian, which covers matter (including amino acids), water, and small calciumsouth-east Asia, southern China, the Indian and Southern Figure 6.A) Chondrules (small rounded grains 1-2 mm across) in L5 ordinary chondrite Kybunga). B) Murchison carbonaceous chondrite showing small calcium-aluminium inclusions (CAIs) that are 5 billion years old and predate the formation of the solar system.47 PREVIEW OCTOBER 2019'