What is the origin of 'sleep tight'?
Read moreOne of the mysteries of the English language finally explained.
A silicate of lead and ferric iron crystallizing in the orthorhombic system and occurring as black to dark grey prismatic crystals.
Late 19th century; earliest use found in Journal of the Chemical Society. From Swedish melanotekit from ancient Greek μελανο- + τήκειν to melt, dissolve + Swedish -it.