Here are my observations, and how I currently classify them. As in, this is my interpretation based on a year or so of burning them on a regular basis. This is by no means objective or particularly scientific, but perhaps it will be helpful.
THE BRIGHT VARETIES
B. Sacra is bright citrus, slightly woody and metallic, with what I can only describe as “blackcurrant” like notes. It’s very refreshing and electric.
B. Frereana is my personal favorite, and has an amazing uplifting scent. It lacks the metallic/blackcurrant like notes of Sacra, and seems to have fruity and floral notes.
THE DEEP VARIETIES
B. Carterii is what I consider the soapy frankincense. It seems to be the most popular, up there with Sacra. It’s woody, soapy, sweet, balsamic and warm. It’s absolutely beautiful. Almost all Frankincense Resinoid products, or Olibanum products offered by the big boys at Robertet etc. use Carterii.
B. Dalzielii is deep and warm, with pronounced honeyed metallic notes. Almost like a deeper Sacra.
B. Papyrifera is similar to Carterii, but has some additional green apple / pineapple nuances to my nose. It’s also dry, sweet, and is reminiscent of the desert.
B. Seratta is sweet, narcotic, slightly spicy. It’s intoxicating. The smoothest and most mellow variety I’ve smelled, and pairs well with Jasmine and presumably other white florals. It brings me to a middle eastern bazaar. It’s just gorgeous, although not particularly strong.
THE WOODY VARIETIES
B. Neglecta is a darker, chalky brown/green frankincense resin with a scent to suit it’s appearance. Very piney, deep woody, with interesting base notes.
B. Rivae is very similar to Neglecta. So much so, in fact, I can hardly tell them apart. Perhaps someone on here could point out their differences?
Protium heptaphyllum also known as Breu Branco or Brazilian Frankincense. It’s a dark chalky bluish resin that is the most woody of them all. Very piney, with cypress-like qualities, pencil shaving type notes. Reminds me of a very, very old bookstore. One of my favorites.
While I haven’t had any luck tincturing Frankincense resin in Alcohol or IPM, some Basenoters have had good luck with frankincense tinctures. I’d love to know their secrets! In the meantime, I will be more than happy to use Frankincense essential oils, resinoids, and other products offered by fragrance companies such as Olibanol (Robertet) and Olibanum Coeur (Ventos).
