Abstract: There is provided a glass-ceramic substrate for an information storage medium usable in an information storage device of the ramp loading system. The glass-ceramic substrate has Young's modulus (GPa)/specific gravity of 37 or over and includes 0 to less than 10 weight percent (expressed on oxide basis) of Al2O3. The glass-ceramic substrate has, as its predominant crystal phases, lithium disilicate (Li2O.2SiO2) and &agr;-quartz (&agr;-SiO2), has a coefficient of thermal expansion within a range from 65×10−7/° C. to 130×10−7/° C. wtihin a temperature range from −50° C. to +70° C. and has a surface roughness (Ra) (arithmetic mean roughness) of 9 Å or below.

Abstract: A high rigidity glass-ceramic substrate for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. A predominant crystal phase of the glass-ceramic substrate consists of one or more crystals selected from the group consisting of &bgr;-quartz, &bgr;-quartz solid solution, enstatite, enstatite solid solution, forsterite and forsterite solid solution.

Abstract: A high rigidity glass-ceramic substrate for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. A predominant crystal phase of the glass-ceramic substrate consists of one or more crystals selected from the group consisting of &bgr;-quartz, &bgr;-quartz solid solution, enstatite, enstatite solid solution, forsterite and forsterite solid solution.

Abstract: A high rigidity glass-ceramic substrate for a magnetic information storage medium has a ratio of Young's modulus to specific gravity within a range from 37 to 63 and comprises Al2O3 within a range from 10% to less than 20%. Predominant crystal phases of the glass-ceramic substrate consist of (1) cordierite or cordierite solid solution and (2) one or more crystals selected from the group consisting of Spinel crystal, Spinel crystal solid solution, enstatite, enstatite solid solution, &bgr;-quartz and &bgr;-quartz solid solution.

Abstract: A glass-ceramic substrate for an information storage medium includes, as a predominant crystal phase, lithium disilicate (Li2O·2SiO2) or a combination of lithium disilicate and at least one crystal phase selected from the group consisting of &agr;-quartz (&agr;-SiO2), &agr;-quartz solid solution (&agr;-SiO2 solid solution), &agr;-cristobalite (&agr;-SiO2) and &agr;-cristobalite solid solution (&agr;-SiO2 solid solution). This substrate has Young's modulus (GPa)/specific gravity of 37 or over, surface roughness Ra (arithmetic mean roughness) of 5.0 Å or below, a coefficient of thermal expansion within a temperature range from −50° C. to +70° C. which ranges from +65×10−7/° C. to +130×10−7/° C. and bending strength of 400 MPa or over.