Translucent glass globules on the Moon

Glass is ubiquitous in lunar regolith,and volcanism and hyper-velocity impacts are the major mechanisms of forming lunar glasses.Volcanic glasses on the Moon occur as quenched skin of basaltic rocks or as glass spherules in pyroclastic deposits.Lunar volcanic glass spherules are less than 1 mm in diameters,and most are less than 300 μm [1].Impact glasses on the Moon are formed by cooling of impact melt and/or condensation of impact vapor,and impact glass spherules have rotational shapes,smooth sur-faces,and largely clast-free interiors [2].Recognized impact glass spherules on the Moon are dominantly sub-millimeter in sizes,and few are up to ～8 mm in diameter [3].Glass spherules record important information about the mantle composition and the his-tory of lunar volcanism and impact cratering [4].Transparent and translucent glasses on the Moon are less than 1 mm in diameters,and larger ones are dark and opaque [5].Hitherto discovered macro-sized glass globules on the Moon (up to ～4 cm in diameter)are opaque impact glass (Fig.1a,b) that usually contains hollows and lithic clasts [6].