Hauyne can be found in association with Igneous, or Metamorphic rock types. The classic locality of Hauyne is considered to be at Monte Somma, Vesuvius, Italy, where the exceptional neon blue colors were initially found. Currently, the most important supply of Hauyne is from a deposit in Germany where it is found in association with alkaline volcanic rocks in the vicinity of Laacher Lake in the Eifel Mountain district. The highest prized specimens of HaŁyne are found here and are of an unusual vibrant neon cobalt blue color.
The German HaŁyne was formed in a magma chamber, with other minerals including plagioclase, sanidine, nosean, nepheline, leucite, apatite, olivine and other alkaline volcanic rocks. It is thought that this eruption occurred more than 12,000 years ago and the Hauyne is revealed in several layers. The area is commercially mined for pumice and basalt but the Hauyne can be collected in the quarries on the weekends.
Other less important localities include; the Canary Islands, Ecuador, the Kokcha Valley of Afghanistan and, in the USA at the Edwards Mine, at St. Lawrence County; in New York, at Winnett, Petroleum County; in Montana and at Cripple Creek, Colorado.
Hauyne forms a solid solution series with Lazurite and shares the same chemical formula but with a variation of the sulfide instead of the sulfate. Crystal forms include octahedral aggregates and dodecahedral crystals which are less common. Hauyne may fluoresce orange-brown in shortwave ultraviolet light.