Crystal structure "white tin" respectively. Two more allotropes, γ and σ, exist at temperatures above 161 °C and pressures above several GPa. White tin is metallic, and is the stable crystalline form at or above room temperature. Below 13.2 °C, tin exists in the gray form, which has a diamond cubic crystal structure, similar to diamond, silicon or germanium. Gray tin has no metallic properties at all, is a dull gray powdery material, and has few uses, other than a few specialized semiconductor applications. Although the α–β transformation temperature of tin is nominally 13.2 °C, impurities (e.g. Al, Zn, etc.) lower the
Selfportrait at 6th wedding anniversary Selfportrait at 6th wedding anniversary Self-Portrait on the sixth anniversary of marriage was painted in Paris. She had moved from Worpswede near Bremen in Germany in February 1906. Modersohn-Becker had decided to leave her husband and Worpswede forever, and devote herself entirely to art. This self-portrait was painted in the spring. She is turned to the right in front of the viewer and she watches the viewer with a searching and questioning look. She has a white cloth on her hip. Her upper body is naked and on her neck she wears an amber necklace. When Paula Modersohn-Becker painted this