| abstract |
A hollow glass microsphere having an average particle size of at most 15 μm based on volume, a maximum particle size of at most 30 μm and an average particle density of from 0.1 to 1.5 g/cm 3 , which has a glass composition consisting essentially of the following components by mass %: n SiO 2 50.0-90.0%, Al 2 O 3 10.0-50.0%, B 2 O 3 0-12.0%, Na 2 O + K 2 O + Li 2 O 0-1.0%, CaO 0-10.0%, MgO 0-10.0%, BaO + SrO 0-30.0%. |