Research has been carried out on the synthesis of amorphous silica (SO2) made from Lumajang sand using the precipitation method. The use of this method is based on its simplicity and can produce large quantities. To increase the synthesis efficiency, nano sand was used, which was processed using high energy milling (HEM) for 15 hours and sintering temperature variations of500°C, 6000C, 7000C, 800°C, and 9000C. The results showed that the leaching process using 2M HCl could reduce crystal peaks and ball milling for 15 hours using HEM produces a sand particle size of 103.8 nm. From the XRD test of five sintering temperatures, amorphous silica occurs at a temperature of7000C, while at other temperatures, crystalline silica peaks still appear. This is supported by the degradation test data, which showed that amorphous silica sintered at 7000C had the highest rate.