Mineralpedia Details for Yukonite
Named for Yukon Territory, the territory in Canada from which it was first found, Yukonite is a secondary mineral that is typically altered from arseopyrite. Found in few localities worldwide, including Canada, USA in New Jersey and Colorado, Germany, and Poland. When fresh, Yukonite may decrepitate, or crackle when exposed to air, water, or heat. This process causes the evolution of carbon dioxide.
Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/yukonite.pdf