Patent ID: 8841222

Claim:
A glass fiber, comprising: a SiO 2 content of 57.0 to 63.0% by weight; a Al 2 O 3 content of 19.0 to 23.0% by weight; a MgO content of 10.0 to 15.0% by weight; and a CaO content of 5.5 to 11.0% by weight, and a total content of SiO 2 , Al 2 O 3 , MgO and CaO of 99.5% by weight or higher based on a total weight thereof, a weight ratio of the SiO 2 content/the Al 2 O 3 content of 2.7 to 3.2, and a weight ratio of the MgO content/the CaO content of 0.8 to 2.0, wherein wherein the SiO 2 content/(the SiO 2 content+the MgO content+the CaO content)×100 is 71.0 or more and 81.0 or less, a devitrification primary phase of the glass is a cordierite crystal or a mixed crystal of cordierite and anorthite, and the glass fiber has an elastic modulus of 95 GPa or higher.