Yes, New Zealands Clutha Schist can be used for exterior applications in cold climates. This natural stone is known for its durability and ability to withstand harsh weather conditions. Clutha Schist has been successfully used in various exterior applications such as cladding, paving, and landscaping in cold climates around the world. It is resistant to freezing and thawing cycles and can retain its strength and aesthetics even in extreme cold temperatures. However, proper installation techniques and sealants should be used to ensure its long-term performance in cold climates.