Yes, Switzerlands Riverstone Phyllite can be used outdoors. Riverstone Phyllite is a type of metamorphic rock that is considered to be durable and suitable for various exterior applications. It is commonly used for outdoor construction projects, such as facades, walkways, landscaping, outdoor sculptures, and more. Its natural beauty, durability, and resistance to weathering make it a suitable choice for outdoor use. However, it is always recommended to consult with a professional or supplier to ensure proper installation and care for the specific application.