Emerald on Calcite from Muzo, Colombia

This emerald specimen comes from the Muzo mining district in the Colombian department of Boyacá. A vivid green emerald crystal sits freely among numerous pale calcite crystals on a dark, finely grained sedimentary matrix.

The emerald shows a distinctly prismatic habit with clearly recognizable lateral crystal faces. Its color ranges from intense green to slightly paler areas. The crystal is predominantly translucent and contains natural internal structures and inclusions. The upper termination is largely flat.

The white to cream-colored calcite covers large areas of the dark matrix. The calcite crystals form a three-dimensional group composed of numerous clearly defined crystals. Small brass-colored ore particles are visible in places between the calcite crystals.

The exposed position of the green emerald creates a strong contrast with the pale calcite and the dark host rock. The specimen can be viewed from several directions while the emerald crystal remains clearly visible.

Measuring 6.3 × 4.5 × 4.0 cm, the piece belongs to the small cabinet specimen size category. It weighs 126.5 g.

Emerald on Calcite from the Muzo Mining District

Muzo is one of the best-known source regions for Colombian emeralds. The emeralds occur there in mineralized fractures and veins within dark sedimentary rocks. Calcite is one of the characteristic associated minerals of the emerald mineralization.

In this specimen, the hydrothermally formed emerald crystal sits within a pale calcite mineralization on a dark, carbon-rich mudstone matrix with a shaly appearance. This preserves the geological relationship between the emerald, calcite, and sedimentary host rock.

The vivid green color, exposed position of the crystal, and contrasting matrix make this a characteristic emerald specimen from Muzo.

Learn more about Muzo in Colombia’s Western Emerald Belt and my impressions of the locality in the detailed Colombia article.

Video of the Emerald Specimen

The video shows the specimen from several angles and illustrates the color and three-dimensional position of the emerald crystal on the calcite.