Calcite

specimen number:
9302273

location:
Dalen-Kjorholt Mine, Brevik, Porsgrunn, Vestfold og Telemark, Norway

description:

Colorless mostly gemmy flattened rhombohedral crystals of calcite to 3.0 cm in size on matrix. This is in great condition and quite nice for the locality.

The Dalen-Kjorholt Mine, located near Brevik in the Porsgrunn municipality of Norway, is a major industrial site renowned for its high-purity limestone and exceptional mineral specimens. Geologically, the mine exploits Ordovician-aged marine limestones of the Oslo Rift, where tectonic activity and hydrothermal processes created large open pockets within the sedimentary layers. These cavities allowed for the growth of world-class calcite crystals, which are famous among collectors for their diverse habits, ranging from sharp rhombohedrons to elongated scalenohedrons. The calcite from this locality is typically transparent to translucent and often exhibits a beautiful honey-yellow, amber, or colorless appearance, frequently showing strong fluorescence under ultraviolet light. Historically, the Dalen and Kjorholt mines began separate operations in the early 20th century to supply raw materials for cement production but were later connected into a single, massive underground complex. Today, while it remains one of the largest underground limestone mines in Europe, it is also celebrated as a classic Norwegian locality for aesthetic and scientifically significant calcite specimens.

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