Maya Jade: Mineral of the Earth Gods

12th Jul 2023

Mexicolore contributor Joaquin Rodriguez

We are most grateful to Joaquin J. Rodríguez III, PE, Administrative Vice President and Director of Research of the Institute of Maya Studies, Florida, an affiliate of the Miami Museum of Science, for this illuminating article introducing the importance of jade to the ancient Maya. The content is technical but no less fascinating...!

Introduction
The Maya valued jade above all materials. The word “jade” comes from old Spanish “piedra de ijada” (ijada being the side space between the ribs and the hip). It’s been translated to English as loin-stone. From the wealth of jade pieces found in Mesoamerica in burials and other structures, it is evident that the stone was an object of great value. Pieces carved by the Olmec from about 1000 BC have been found with images of deities and anthropomorphic figures. Scholars have concluded that jade was part of the spiritual and ritual life of ancient Mesoamerica. Some of these pieces were found hundreds of years later in Maya tombs, proving that they were considered heirlooms by the Maya elite of the Classic period.

Mineralogy
What we call true jade can be of two different mineral constituencies. Jadeite or nephrite, both of which are mineral groups that are the result of high metamorphism, formed under extremely high pressure and heat at tectonic plate boundaries.
Jadeite is a pyroxene mineral with composition NaAlSi{superscript2O{superscript6. It is monoclinic. It has a Mohs hardness of about 6.5 to 7.0.

Nephrite is a rock comprising mostly amphiboles of the tremolite-actinolite series. White nephrite, termed white jade or mutton-fat jade, is nearly pure tremolite, while most nephrite is green owing to the Fe content in actinolite. Chromium colors nephrite emerald green and yellow to brown nephrite is stained by iron oxides and hydroxides introduced along grain boundaries. Mohs hardness of about 6.0 to 6.5. Actinolite, the main mineral in Nephrite jade is an amphibole hydrous silicate mineral with a chemical composition Ca2(Mg4,Fe2)Si8O22(OH)2.

Most New World jade is jadeite, while most Asiatic jade is nephrite. While some sources of jade occur in California, along the northern reaches of the San Andreas Fault or in northern Venezuela, the main sources of jadeite in Central America are along the Motagua Fault that marks the contact point of the Caribbean plate (that forms Central America) and the southern edge of the North America Plate (see Map 1). This locked fault, that splits Guatemala in two, along which the Motagua River now flows, marks a high metamorphic zone where two continents smashed together about 70 million years ago.

It is on the mountain slopes of this fault, appropriately called Sierra de Minas (Range of mines) where most jadeite is found, even to this day. (See Map 2).
Pyroxenes and amphiboles are hard to tell apart. Both are monoclinic (meaning one crystal lattice axis is inclined to the other two). Pyroxenes form angles of 87 and 93 degrees while amphiboles form angles of 124 and 56 degrees. This can only be differentiated under X-ray diffraction crystallography.

Lapidary
Jadeite is a lapidary’s ideal stone: vivid colors, hard enough to be durable but not so hard as to be unworkable. It is an anisotropic stone (meaning the properties are different in different directions) with a hardness of 6.5 on the weak axis to 7 on the hard, it can readily be worked with a quartz point (hardness 7) and polished with silica sand (mostly quartz at h7) with common inclusions of corundum (h 9) and staurolite (h 7.5). It can also be cut with abrasion string wetted and with silica sand adherent; or drilled with a rotating stylus and same silica sand.
Although jadeite comes in all colors green was the preferred for ornamentation for the obvious reference to vegetation, and therefore life and the Maize God.

Jade-like minerals
Although it is referred to as “Maya Jade,” it is doubtful that the Maya differentiated between the various green minerals (or could). They simply referred to ya’axil tun (green stone), any green stone of durable hardness was precious to them, and indeed there are several.

Chrysoprase is a brittle, translucent, semiprecious chalcedony, a variety of the silica mineral quartz. It owes its bright apple-green color to nickel silicate; heating or prolonged exposure to sunlight will cause the color to fade. Its physical properties are those of quartz; Mohs hardness 7.

Amazonite: “Amazon stone” is a green variety of microcline feldspar; KAlSi{superscript3O{superscript8; Color: Blue, Green, Purple, Hardness 6 - 6.5 Crystal System: Triclinic.

Soapstone (Also known as steatite or soaprock) is a talc-schist, which is a type of metamorphic rock. It is largely composed of the mineral talc (Mg{superscript3Si{superscript4O{superscript10(OH){superscript2) with Chlorite and is thus rich in magnesium. It is produced by metamorphism, which occurs in the areas where tectonic plates are subducted, a medium for carving for thousands of years. Mohs hardness of about 3.5 to 5.0. The main constituent, talc, would make it very soft but the same inclusions of chlorite, which colors it green, raises its hardness.

Serpentine is not a single mineral, but rather a group of related minerals. The main members are: Antigorite and Chrysotile - Mohs hardness of about 3 to 5.0.
Soapstone and Serpentine, being the softer of the group would be ideal for carving into statuary, while Chrysoprase, being a form of chalcedony (like agate, flint and chert) can be knapped. All these minerals and rocks (with the exception of Chrysoprase) would be found in metamorphic environments.

Chrysoprase (like all the chalcedonies) is of sedimentary chemogenic origin. Ph changes in the environment cause silica (SiO2) to precipitate out of water and deposit in cryptocrystalline (very small crystal) structure in cavities of limestone where they form nodules.

Conclusion
Whatever the mineralogy the Maya and other Mesoamerican cultures have left us, these beautiful objects of ya-axil-tun that represent their beliefs and aesthetics, are a credit to their technology, economy and trade.

Picture sources:-
• All images kindly supplied by the author.