Yes, Brazils Blue Magma Quartzite can be used for exterior applications in very humid climates. Quartzite is a natural stone that is highly resistant to water absorption, making it suitable for outdoor use. It is a durable and hard material that can withstand various weather conditions, including humidity, without deteriorating or warping. However, it is always recommended to properly seal and maintain the stone to ensure its longevity and to protect it from potential staining or discoloration caused by prolonged exposure to moisture.