<p>Weathering is the breakdown of rocks and minerals through physical, chemical, and biological processes, while deterioration refers to the gradual decline in the condition of materials or structures. Studying them is essential to preserve natural landscapes and maintain the stability of infrastructure. Quartzite, widely used in railway ballast, is subjected to mechanical stresses and environmental degradation over time. The study investigates the deterioration characteristics of quartzite ballast from four quartzite units of the Lesser Himalaya, namely the Fagfog Quartzite, Dunga Quartzite, Pandrang Quartzite, and the Chisapani Quartzite, under cyclic weathering processes such as slake weathering and freeze–thaw weathering. The quartzite samples, classified as monomictic and sourced from age of Precambrian, were analyzed for two key durability properties: Slake durability index and sulfate soundness value. These properties are essential in assessing the suitability of quartzites for construction, especially in environments exposed to cyclic weathering and chemical attack. The quartzites from the Fagfog Quartzite showed the greatest variability in slake durability index values, with some samples displaying progressive disintegration. The sulfate soundness value test highlighted significant differences among the quartzites, with Dunga, Pandrang, and the Chisapani Quartzites showing higher resistance to sulfate-induced degradation. Quartzites from the Dunga Quartzite and the Pandrang Quartzite are resistant to slaking, and freeze and thaw weathering, reflecting more suitable for environments prone to cyclic weathering and sulfate or freeze–thaw exposure. In contrast, the quartzites from the Fagfog Quartzite and the Chisapani Quartzite, though generally durable, showed more variability in resistance. These findings provide critical insights into the durability of quartzite for railway ballast and other construction applications.</p>