Classic lustrous calcite twin from the Tri-State district. The angle of twin is clearly evident on termination and contact plane runs sharply across crystal surface. Mined ca. 1950s. Condition: excellent. Provenance: Jim DuFoe Collection #M2614; sold to Charles Noll #CN3709; donated to Marquette University; brokered by Seaman Museum; sold to Ross Lillie Tucson 2016. Note: this is one of the few Tri-State twins I have handled that has not been acid-dipped.