Basalt Clay products, our dark side. These products are based on antique clay added to a natural mineral ore which causes grey to brown up to give an anthracite marble effect color to the pots. Depending on the processing and combination of clay’s the color of basalt products may vary from darker to light as well as from brownish to dark grey which gives each item an individual appearance. You can choose from a wide range of shapes and sizes, from bowls to window boxes and everything in between and add a saucer for indoor use. Efflorescence are an important part of these products, they are not a product defect.