It seems the extensive discussion we had a while ago on slag glass, malachite and cloud glass did not have much of an impact.
Slag glass is an opaque product of milk glass with a colour, i.e. you cannot look through it. The purple and white variety is normally called slag glass. The German name is Schmelzglas (melted glass) - the Venetians knew it by the name of Calcedonio.
"Malachite" was a company name for a range of wares, however, malachite is green so to use it for another colour was - and is - a misnomer. Green Malachite glass is still being made at Desna, in the Czech republic, so there is great potential for confusion.
Cloud glass is a Davidson company name for pressed ware in transparent glass with colour streaks.