Colourful lakelets (Polish "Kolorowe Jeziorka") is the name of three (sometimes four) artificial ponds formed in place of former mines at the slope of Wielka Kopa mountain (871 m) in Rudawy Janowickie, range in Sudetes Mountains, Poland.
The biggest one and the oldest (1785) was named Hoffnung Grube and now hosts the Purple lakelet.
The Purple lakelet (560 m) owes its colour to chemical composition of its banks and bottom which are abundant with iron compounds, mainly pyrite.
The pond is filled with water solution of sulphuric acid (pH = 3).
The colour of Azure Lakelet (635 m; also called: Blue or Emerald) water is connected with the presence of copper ions.