Yes, Greeces Sykis Quartzite can be used for exterior applications in cold climates. Quartzite is a very durable and hard stone, which makes it suitable for outdoor use even in harsh weather conditions. It is resistant to freeze-thaw cycles, meaning it can withstand the expansion and contraction that occurs when water freezes and thaws, which is common in cold climates. However, it is always advisable to consult with a professional stone supplier or installer to ensure that the specific type and quality of quartzite is suitable for your particular project and climate.