1.4" Orange Stilbite and Calcite Association - Strzegom, Poland
This is a beautiful, 1.4" wide stilbite and calcite association that was collected from Strzegom, Poland. The stilbite is orange-brown in color and formed from a calcite crystal encrusted matrix.
Stilbite is probably the most common zeolite found in these deposits. Crystals often form flowery, bowtie or hourglass shaped structures and come in a variety of colors. Some of the most beautiful colorations are the pink or peach tints.
Calcite, CaCO3, is a carbonate mineral and the most stable polymorph of calcium carbonate. The other polymorphs are the minerals aragonite and vaterite. Calcite crystals are trigonal-rhombohedral, though actual calcite rhombohedra are rare as natural crystals. However, they show a remarkable variety of habits including acute to obtuse rhombohedra, tabular forms, and prisms. Calcite exhibits several twinning types adding to the variety of observed forms. It may occur as fibrous, granular, lamellar, or compact. Cleavage is usually in three directions parallel to the rhombohedron form.