The family Burseraceae with 17 genera is widely distributed in tropical and subtropical countries. Boswellia has about 20 species in the dry regions of tropical Africa, Arabia and India. The resin obtained from Boswellia species is known in common parlance as frankincense or olibanum and is used as incense. The recent botanical report on the Burseraceae of Ethiopia has revealed the occurrence in Ethiopia of six Boswellia species namely Boswellia papyrifera, B. pirottae, B. rivae, B. ogadensis, B. neglecta and B. microphylla (Vollesen, 1989).

Boswellia is a genus of trees known for their fragrant resin which has many pharmacological uses particularly as anti-inflammatories. The Biblical incense frankincense was probably an extract from the resin of the tree, Boswellia sacra.

There are four main species of Boswellia which produce true Frankincense, and each type of resin is available in various grades. The grades depend on the time of harvesting, and the resin is hand sorted for quality. Anyone interested in frankincense would be well advised to first obtain a small sample of each type from a reputable dealer to ascertain the difference between each resin.

Boswellia sacra (syn. Boswellia carteri, Boswellia thurifera) is the Arabian Frankincense, and the best quality comes from the Oman and Yemen. According to western buyers, the highest grades are known as Silver and Hojari. Although the Omanis themselves generally consider Silver to be a better grade than Hojari, most Western connoisseurs think that it should be the other way round. This may be due to the climactic conditions with the Hojari smelling best in the relatively cold, damp climate of Europe and North America, whereas Silver may well be more suited to the hot dry conditions of Arabia.

Local market information in Oman suggests that the term Hojari encompasses a broad range of high-end frankincense including Silver. Resin value is determined not only by fragrance but also by color and clump size, with lighter color and larger clumps being more highly prized. The most valuable Hojari frankincense locally available in Oman is even more expensive than Somalia’s Maydi frankincense derived from Boswellia frereana. Most of this ultra-high-end Boswellia sacra frankincense is purchased by His Majesty Sultan Qaboos bin Said the ruler of Oman and is notoriously difficult for western buyers to correctly identify and purchase.

Trees in the narrow fog-laden zone where the desert meets Oman’s southern mountain range, a region known as the Nejd, grow extremely slowly and produce very high-quality resin in large, white clumps. Not surprisingly, Omanis and other Gulf State Arabs consider this to be superior to all other resins produced in North and Northeast Africa, India, and Asia, and it is priced accordingly.