Clay with a high concentration of this mineral is more susceptible to dunting when firing a kiln because it changes from its alpha to its beta form at 573 degrees Celsius. To save cost, PZT is sometimes used to replace this mineral in a system developed by George W. Pierce. This mineral is the most resistant to weathering on the (*) Goldich (10[3])dissolution series. (10[5]0[1])Because of its low crystallization temperature, this mineral appears (10[1])at the bottom (10[1])of Bowen’s (10[5])reaction (10[6])series. (10[1]0[1])Microcrystalline (10[1])forms of this mineral make up different types of chert, like agate and onyx. This mineral’s piezoelectric (10[2])properties (10[3])enable (10[1])its use in digital watches. (10[3])For 10 points, a value of seven on the Mohs hardness (10[1])scale corresponds to what mineral made up of silica? (10[2])■END■