Emeralds from the Fazenda Bonfim region, Rio Grande do Norte, Brazil

J. C Hanco Zwaan*, Dorrit E. Jacob, Tobias Häger, Mário T O Cavalcanti Neto, Jan Kanis

*Corresponding author for this work

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

In 2006, emeralds were discovered in the Fazenda Bonfim region of northeastern Brazil. Emerald mineralization occurs in association with small recrystallized pegmatitic bodies hosted by metamorphosed ultramafic rocks within the Santa Monica Shear Zone. Prospecting and exploration have been carried out in a few small pits and tunnels, producing emerald crystals with transparent areas that typically range between 2 and 5 mm. Polished samples typically show a saturated bluish green color with a medium-light to medium tone. The most common internal features are partially healed fissures with two-phase (liquid-gas) fluid inclusions and a variety of fine, parallel-oriented growth tubes. The emeralds contain moderate amounts of the chromophore elements Cr and Fe, and traces of V; they also show relatively high K and low Li. FTIR spectroscopic features are consistent with alkali-bearing emeralds that contain considerable CO 2 and a small amount of deuterated water. Emeralds from Fazenda Bonfim can be distinguished from those of other schist-and pegmatite-related commercial deposits.

Original languageEnglish
Pages (from-to)2-17
Number of pages16
JournalGems and Gemology
Volume48
Issue number1
Publication statusPublished - 1 Apr 2012
Externally publishedYes

    Fingerprint

Cite this

Zwaan, J. C. H., Jacob, D. E., Häger, T., Neto, M. T. O. C., & Kanis, J. (2012). Emeralds from the Fazenda Bonfim region, Rio Grande do Norte, Brazil. Gems and Gemology, 48(1), 2-17.