Often these slag piles are later reclaimed for their now more valuable metals by modern techniques that can extract profitable amounts of metal from these lower grade ores. Mineralogists often consider these slag piles to be valuable as collecting sites for rare and sometimes unknown minerals. Such is the case for laurionite and paralaurionite. Although both have been known for over a century, like them, many minerals were and are being discovered in lead slag piles, sometimes leftover from mining operations that stopped centuries before. Laurionite forms small colorless vitreous to adamantine crystals often with distinctive V-shaped striations on the prism faces.
Crystals are prismatic to acicular and brittle.
Paralaurionite forms minute tabular colorless, white or pale yellow crystals without striations and they are nonbrittle, flexible but inelastic. Color is colorless to white. Luster is vitreous to adamantine. Transparency crystals are transparent to translucent. Crystal System is Orthorhombic.