Aromatic Note: Base note – fixative
Onycha is a mysterious incense ingredient mentioned in the Christian bible; Exodus 30:34:
And the Lord said to Moses, “Take sweet spices, stacte, and onycha, and galbanum, sweet spices with pure frankincense (of each shall there be an equal part), and make an incense blended as by the perfumer, seasoned with salt, pure and holy; and you shall beat some of it very small, and put part of it before the testimony in the tent of meeting where I shall meet with you; it shall be for you most holy. And the incense you shall make according to its composition, you shall not make for yourselves; it shall be for you holy to the Lord. Whoever makes any like it to use as perfume shall be cut off from his people.”
The reference does not give any indication as to what Onycha is so we must start with the name itself, which is a Greek word for “fingernail,” translated from the Hebrew, “Sheheleth“* and is applied to an operculum, defined as, “the claw or nail of the strombus or wing-shell, a univalve common in the Red Sea.”
With the name of the ingredient meaning “fingernail” and/or “a univalve claw or nail” we can now examine the various theories around the world as to what this mysterious ingredient may be.
Labdanum – this is the resin secreted by the Rock Rose Bush. The argument for this ingredient to be the mysterious Onycha is that the markings on the flower petals of this plant are in the shape of a fingernail.
Gum Tragacanth – this is the gum resin from the Astragalus plant species. This resin forms in grotesque fingernail shapes. Refined Tragacanth gum is widely used as a binder for making incense sticks, cones and pellets.
Mollusk Opercula – the “lid” of a small whelk-like shellfish that is secreted around their shell opening in order to seal themselves in during dry periods.
To many, this opercula lid has the most potential of being the true Onycha. The dried lids look like fingernails and since ancient times have been known to be widely used as a fixative in incense mixtures in the India, Tibet, and Japan. Each prepare the opercula using different methods.
In Japan the same ingredient is called “Kaiko,” and it’s soaked or slowly heated in a mixture of water and vinegar or alcohol to remove the shellfish aroma, then ground and used as a fixative in their incense mixtures.
In Tibet, the opercula lids are crushed, placed in a pan of oil and slowly heated to draw out a resin from the lids into the oil. This resin-filled oil is then used in high quality incense mixtures.
In India, the lids are slowly heated in Ghee (clarified butter) several times until they golden in color. These are then dried, crushed, and used in high-end incense mixtures as a fixative.
If we trace the origin of the Exodus mixture itself, to the Hebrew Qetoret, we find that there are sixteen ingredients in the incense recipe given to Moses (see Qetoret). In it, Onycha is “rubbed with Karshina lye to make it more pleasant and then soaked in Cyprus wine to make it more pungent.“
This prescribed processing would eliminate labdanum as Onycha because labdanum is already a wonderfully aromatic ingredient and needs no treatments to make it more pleasant or pungent. It also has no connection to the root meaning of the original Hebrew word.
So we’re left with gum tragacanth and a group of sea mollusks. Using the information that this same group of Red Sea mollusks are used by incense masters all around the world, the ingredient is a superb incense fixative, requires processing before its use and associates with the Hebrew root of the word Sheheleth, which defines a sea mollusk.
This compares with gum tragacanth, which for incense, is used primarily as a binding material to form sticks, cones and pellets, and not as an aromatic ingredient or fixative.
Gum tragacanth in its raw form has the appearance of long, grotesque fingernails but it exudes from a tree and not the sea, as the root of the Hebrew word suggests. Also, if gum tragacanth were to be processed as the Hebrew recipe requires, it would dissolve.
We conclude that the biblical Onycha is most likely the dried and processed secreted lids of a group of Mollusk Opercula found primarily in the Red Sea (as pictured above).