Vitrified sand

Vitrified sandissandthat has been heated to a high enough temperature to undergovitrification,which is the melting of thesilicon dioxideorquartzthat compose common sand. Vitrified sand is a type of naturalglass,contrasted with manufactured glass in whichsoda ashorpotashare added to lower the melting point. Pure quartz melts at 1,650 °C (3,002 °F). There are several natural processes that produce more or less melted sand and one man-made form:

• fulguriteis sand fused by a lightning bolt hitting sand.
• Impactitesuch astektiteis sand fused by the compressive heat of a meteor strike includingmoldavite,a gem quality stone mined in some locations.
• fritis partially fused sand plus other chemicals created in the process of glaze and glass making.
• Nuclear melt glass, formed by the detonation of a nuclear weapon. Examples includetrinitite,created during theTrinity nuclear test

Volcanic glassin many forms is not fused sand because it is formed from molten material.