Tin(II) sulfide Tin(II) sulfide Tin(II) sulfide is a chemical compound of tin and sulfur. The chemical formula is SnS. Its natural occurrence concerns herzenbergite (α-SnS), a rare mineral. At elevated temperatures above 905K, SnS undergoes a second order phase transition to β-SnS (space group: cmcm, No. 63). in recent years, it has become evident that a new polymorph of SnS exist based upon the cubic crystal system, π-SnS (space group: P23, No. 198). Tin(II) sulfide can be prepared by reacting tin with sulfur, or tin(II) chloride with hydrogen sulfide. Tin(II) sulfide is a dark brown or black solid, insoluble in water, but
Gift economy Gift economy A gift economy, gift culture, or gift exchange is a mode of exchange where valuables are not traded or sold, but rather given without an explicit agreement for immediate or future rewards. This exchange contrasts with a barter economy or a market economy, where goods and services are primarily exchanged for value received. Social norms and custom govern gift exchange. Gifts are not given in an explicit exchange of goods or services for money or some other commodity. The nature of gift economies forms the subject of a foundational debate in anthropology. Anthropological research into gift economies began