Knotenschiefer

The node shale is next to the Fleck shale, shale fruit and the sheaf slate a variety of kontaktmetamorphen slate. Node shale occur at temperatures around 400 ° C and their dark color is caused by graphite. From 500 ° arise fruit shale. Node shale is characterized by up to centimeter-sized nodules and nodular mica layers due to grain growth during metamorphosis. The nodes consist of iron minerals, carbonaceous substances and mica, with increasing metamorphic grade are increasingly added minerals such as andalusite.