How to verify frankincense species and quality before you buy

The species on a frankincense offer is a statement somebody made, somewhere between the tree and the invoice. In the best-documented case, 9 of 13 commercial oils sold as pure Boswellia carterii contained the marker of a different species.¹

Below is what you can check before you buy, in what order, and what each check leaves open. It applies to any supplier, including us.

Why the species on an offer can be wrong

Boswellia occulta was described as a new species in 2019, from Ceel Afweyn District in Sanaag, Somaliland, where harvesters had tapped it for generations.² Harvesters in its area call it mohor madow, and call Boswellia sacra mohor cad, mohor dadbeed or mohor lab.² Even so, both trees go by the name mohor, the resin of both is called beeyo, and the two resins are frequently mixed.^1,3

The oil of B. occulta is dominated by methyl ethers: 1-methoxydecane made up 26.6 to 47.9% of the oil from twelve single trees, and 1-methoxyoctane 3.6 to 8.6%.³ It was 1-methoxydecane that turned up in 9 of the 13 commercial oils.¹

Maydi, the resin of Boswellia frereana, is not exempt: none of twelve single-tree samples contained methoxyalkanes, and the authors conclude that commercial B. frereana oils containing them are mixtures with B. occulta.^4,5

Organic certification did not prevent it: 5 of the 13 oils were certified organic, and 4 of those contained the compound.¹ The study’s authors call certification useful against chemical contamination but not sufficient to guarantee purity in a wild-harvested product, and they recommend traceability and verification alongside it.¹ A separate study of the Somaliland harvest describes organic certification as ineffective at distinguishing the source trees, and so at establishing whether they were harvested sustainably.⁵

One species, two names

Kew’s Plants of the World Online accepts Boswellia sacra and lists Boswellia carteri as a synonym.^6,7 A review by the Royal Botanic Garden Edinburgh calls carteri a superfluous and illegitimate name, and after measuring 37 characters found none that separates Arabian trees from Somali ones.⁸

The trade still uses the synonym, usually spelt carterii, and uses it to mean origin: a European market guide describes B. carterii as found in Somalia and East Africa and B. sacra as growing in Oman and Yemen.⁹ The habit has some chemistry behind it, since one survey could tell Omani from Somali resin by its triterpenic acids.¹⁰

So carterii on an offer tells you which origin the seller means, not who identified the resin or how. Ask for the accepted name and the trade name together, and check that the offer, the certificate of analysis and your own files agree.

What to check, and in what order

Take the checks in order. Each narrows what the next has to answer.

What to check	How	What it tells you
1. Who identified the resin	Ask who, at what point, and whether by eye or by analysis.	What the species name rests on. An identification by eye is a judgement, not a test result.
2. Collection area and date	Ask for the lot list or purchase records.	Which harvest the resin belongs to, and whether any of it comes from the area where B. occulta is known to grow.1 Not what is in the bags.
3. A sample of the lot	Have it drawn from the lot on offer. Ask how it was drawn.	What this lot looks and smells like. A sample of another lot tells you about another lot.
4. GC-MS of the lot	Distil the sample and analyse the oil. Ask for 1-methoxydecane to be reported by name.	Whether the marker of B. occulta was detected in that sample.3 For maydi, whether the oil is consistent with published B. frereana data.
5. Moisture and foreign matter	Have both measured on the sample, against limits written into the specification.	How much of the weight is resin. Nothing about species.
6. The documents	Ask for the technical data sheet, safety data sheet and certificate of analysis.	Whether the analysis you were shown belongs to the lot you are buying.

The word beeyo does not settle the species, because harvesters use it for the resin of both trees.¹ Ask whether the people buying at origin know mohor madow by name, and whether it is kept apart.

B. occulta appears to inhabit a limited range, mainly around the towns of Ceel Dibir and Bildhalaay in western Sanaag.¹ A lot collected there needs the marker test more than most. A lot from elsewhere is lower risk, not cleared. The date tells you which season’s resin you are looking at: beeyo is a summer harvest and maydi a winter one.⁵

Reading a GC-MS result

For resin, GC-MS means distilling a little first and analysing the oil, as the single-tree studies did.^3,4 A report that shows 1-methoxydecane points to B. occulta resin in that sample.¹ A report without it means the marker was not detected in that sample, at that laboratory’s reporting limit. Neither result speaks for bags that were not sampled, so ask which bags the sample came from.

For maydi, the oils of twelve single trees held 14.5 to 43.9% α-thujene and 3.0 to 63.0% α-pinene.⁴ Ranges that wide show consistency at most. They cannot identify the species, because both compounds are also among those that dominate the oils of other Boswellia chemotypes.¹

Boswellic acids are a sharper check for maydi, because two independent studies found none in B. frereana resin.^4,10 A maydi lot that contains them does not match the published data. The assay is no test for B. occulta in beeyo: the one B. occulta sample in the second of those studies contained 13.4% boswellic and lupeolic acids.¹⁰

Moisture, foreign matter and documents

Resin is sorted and graded by size, colour and cleanliness before export.¹¹ A grade is not a measurement. If water, bark or stone matters to your process, write a limit and a test method into the specification. Our article on grades has specification lines you can copy.

European buyers expect a technical data sheet, a safety data sheet and a certificate of analysis, the last giving laboratory results for a batch.¹² Check that the certificate names the lot number on the bags, the laboratory, the method and the date. A typical analysis describes a product. It does not certify your lot.

What published values can and cannot tell you

Somali B. sacra resin typically yields 4 to 8% essential oil, and more than one chemotype of the species has been identified.¹ Twelve single trees of B. occulta yielded 2.68 to 5.45%.³ In B. frereana, α-pinene ran from 3.0 to 63.0% across twelve trees collected near one town.⁴

Figures like these describe the trees that were sampled. They are not a specification for your lot. That is what you and the supplier agree in writing, and the evidence for it is an analysis of the lot. Our frankincense sheet lists what is fixed for every order and what a laboratory can test.

Questions to put to any supplier

• Who identified this resin, at what point, and by what method?
• Which name are you using, B. sacra or B. carterii, and what do you mean by it?
• Where and when was each bag collected, and what record shows it?
• Was the sample drawn from the lot on offer, and from which bags?
• Has this lot itself been analysed by GC-MS, by which laboratory and when, and was 1-methoxydecane reported?
• What are your limits for moisture, bark and stone, and how are they measured?
• Which certificates do you hold, and what does each one cover?

The limits of identifying resin by eye

On the tree the difference shows: B. occulta is the only Boswellia known outside Socotra with simple leaves.² Resin in a sack has no leaves. A published description does separate the two main types, with beeyo milky and yellow-brown and maydi in large golden tears.⁵ B. occulta resin is another matter. It is traded as beeyo, and it was GC-MS that found it in commercial oils.¹

Our own identification has these limits. Type, beeyo or maydi, is judged by eye by the person who buys the resin. That is a judgement and not a laboratory result, and it cannot rule out B. occulta. So put the mohor madow question to us as well: the answer for a given lot is its collection area, which is on the lot list, and a GC-MS screen if you ask for one.

What we can show you is the record. Every purchase is written down with who sold it, where, when and the price paid, and the lot list ties each bag to its collection area and date. See what we record for every lot and a demonstration lot record.

Before you order, we send photographs and a sample of the lot itself. Laboratory analysis such as GC-MS and moisture is arranged on request, through an outside laboratory. We hold no organic or other third-party certification. Request a sample and test it as you would test anyone’s.