There is a trade-off in terms of slightly lower solubility, but the improved strength is of help, particularly in making such products as blankets, in which the fibres are needled to form an interlocking web of fibres. [0040] Accordingly, the present invention comprises a silicate fibre comprising: [0041] 65%<SiO2<86% [0042] MgO<10% [0043] 14%<CaO<28% [0044] Al2O3<2% [0045] ZrO2<3% [0046] B2O3<5%