White Santorini Quartzite, like other natural stones, can be used for exterior applications in cold climates. However, it is important to consider a few factors before making a final decision:

1. Frost Resistance: Quartzite is generally resistant to freezing temperatures, making it suitable for cold climates. However, its always recommended to verify the specific type of quartzite being used, as some variations may have different levels of frost resistance.

2. Thermal Expansion: Natural stones, including quartzite, can expand and contract with temperature changes. In extreme cold climates, where there are rapid and severe temperature fluctuations, this thermal expansion can lead to stress within the stone. It is crucial to consult with a professional stone specialist or supplier to ensure the suitability of the specific quartzite variety you are considering.

3. Sealing: Proper sealing of the quartzite is essential to enhance its durability and protect it from moisture penetration, which can cause cracking or damage in cold climates. Regular maintenance and resealing might be necessary to ensure the stones longevity and performance in exterior applications.

4. Installation: Adequate installation techniques and specific industry standards should be followed, especially when it comes to exterior applications in cold climates. Improper installation may result in water infiltration, freeze-thaw damage, or other structural issues.

Before using White Santorini Quartzite or any natural stone for exterior applications in cold climates, it is always advisable to consult with a professional stone supplier or installer to assess its suitability, consider local climate conditions, and ensure proper maintenance and sealing procedures are followed.