I dont have access to the latest data or information on Wanaka Schist slabs in New Zealand. However, based on some online sources, Wanaka Schist is available in thicknesses ranging from 10mm to 50mm for slabs. The thickness can vary depending on the application and needs of the project. It is recommended to consult a local supplier or stonemason for specific information on Wanaka Schist slabs.