Quartz sand is one of the widest-spread minerals in Latvia. The perspective of using Latvian quartz sand from deposits Bale (Devonian period) and Skudra (Jurassic period) in glass production industry were examined. Previous studies have shown that the sand obtained from these minefields exhibit rather high amount of SiO2 (<98%) but also elevated amount of ferrous and aluminum oxides. The dominating granulometric fraction in these minefields is 0,1-0,5 mm. Due to high requirements in terms of chemical composition and particle size distribution brought forward by glass manufacturing process the pretreatment and enrichment of Latvian sand is needed. In current study milling of sand in dry state and in the presence of water has been performed. Crystalline phases have been determined before and after treatment using X-ray diffraction. Differential thermal analysis has been performed in order to evaluate the potential polymorphic transformations. The glass has been melted using the pretreated sand and other components according to the proportions practiced at JSC „Valmieras stikla skiedra”. The dependency of the glass thermal linear expansion coefficient and glass transition temperature on the milling environment (with or without addition of water) has been observed. The obtained results showed that milling of sand from Skudra deposit in the presence of water resulted in an increase of SiO2 content while amount of ferrous reduced (down to 0,006%). It has been concluded that quartz sand from Skudra deposit can be successfully used in glass manufacturing if an appropriate pretreatment is performed. Milling with simultaneous water treatment is an economical, environmentally friendly and efficient pretreatment method which can be implemented for this purpose.