By condensation on hot substrates and by annealing above 204°C selenium crystallizes in the direction of the chain molecules (needles, crystals like round paving-stones). From the fluid or amorphous phase selenium crystallizes perpendicular to the chain molecules (biconvex crystals, fibrilles, spherulithes). The biconvex crystals are macroscopical examples for crystal seeds of substances consisting of chain molecules. They may become cores of spherulithes if the growth proceeds in a sheaf-like manner. In thin layers rows of fine fibrilles are formed by trans-crystallization at about 115°C. Such layers show a fibre texture ([100] – fibre axis). The plane of cleavage is (10[unk]0).