Often called butterfly twins for their outstretched wings, this is a fine, sharp example of the amazing twinned calcites found in basalt cavities, which came out of Brazil in the late 1990s. Unprecedented from Brazil in form and style, these came out briefly and then have not since. The deposits in this region are huge and with many basalt cavities filled with calcites - yet, twins were always very rare and this remains a one time find from decades ago. A 2.6 x 2.1 x 0.8 cm transparent to translucent colorless twin crystal, this stands on its own merits as a superb thumbnail-sized calcite twin regardless of locality. It also fluoresces orange in longwave UV, perhaps due to slight manganese content.