MINERALOGICAL STUDIES ON GUATEMALAN JADE

The earliest recognized use of jade was by the inhabitants of the Neolithic lake dwellings of Europe. The use of jade in the form of ceremonial celts was widespread in the islands of the Pacific Ocean.

NO. 5 GUATEMALAN JADE — FOSHAG 9

Thus, in a strangely indirect way, the "piedra de yjada" of the Spaniards became associated with the name of the modern mineralogical species of jadeite. Nephrite: A compact variety of the mineral tremolite (calcium magnesium silicate) or actinolite (calcium magnesium iron silicate), mineralogical species of the amphibole group of minerals.

GEOLOGICAL OCCURRENCE

A mineral closely related to jadeite occupies a mineralogical position between it and its pyroxene congener, diopside, a silicate of calcium and magnesium. Another closely related mineral has a chemical composition that is between jadeite and acmite, a sodium iron silicate, the iron analogue of jadeite, or between jadeite, acmite and diopside.

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NO. 5 GUATEMALAN JADE — FOSHAG 13

CHEMICAL PROPERTIES

OPTICAL PROPERTIES

Many minerals (optically biaxial group) have three different refractive indices corresponding to the three main directions in the crystal lattice of the substance. The determination of the average index (w) is sufficient to distinguish deite and its relatives from other minerals used in the indigenous cultures of Mesoamerica.

NO. 5 GUATEMALAN JADE — FOSHAG IQ

NO, 5 GUATEMALAN JADE — FOSHAG 21

JADE TYPES

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Other dark-colored rocks such as diorite or diabase can be confused with this mineral, but of the 269 black Celts in the examined collections of the Institute de Antropologia e Historia de Guatemala, 225, or 83 percent, were made of chloromelanite. Apparently the chlormelanite objects were of a practical nature: Celts of various shapes (Kaminaljuyu, 3197; Uaxactiin, 483, etc.), chisels, reamers, etc. Potters in Chinantla claim to look for these polishing celts in the surrounding hills.

Several of the elaborately carved celts in several collections appear to be simple chloromelanite celts with later false carvings. The Celts in this material are represented in the collections of the Institute de Antropologia e Historiade Guatemala from Chukmuk, Chutex-Tiox, Guatemala (Roosevelt Hospital), Kaminaljuyu, Los Cerritos, Nebaj, San Agustin Acasaguastlan, San Andres Sajcabaja, Uaxactun, Xa -pom, Zacaleu and Zacualpa. Many of them owe their inconspicuous character to impurities and poor stone quality or surface blemishes.

OTHER MINERALS

In thin section, under the microscope, the material consists of a mosaic of clear, unconnected albite grains with interspersed, etched, ragged prisms of jadeite (w = 1.665). It is interesting to note here the occurrence of jadeitic and horn-mixed albite with jadeite at Manzanal, discovered by Robert Leslie. Beryl.– The only mention of beryl being used by the early indigenous people is a reference by Antonio de Herrera.

The Robles Collection, Quetzaltenango, contains three rough pieces of beryl (aquamarine) found in a tomb near Salcaja.

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This distinctive material has particular significance for archaeological studies, as it is easily recognized and has a wide distribution in Mesoamerica. It is abundant in the form of beads and figurines in the state of Guerrero, Mexico, which appears to be the center of its distribution, but with what culture it is associated is still unknown. All sites where extensive excavations have been conducted have yielded some artifacts of this material, from Piedras Negras and Uaxactun in the Peten to the Pacific coast, including Kaminaljuyu, San Agustin Acasaguastlan, Quetzaltenango, and the Quiche.

Its specific gravity varies from 3.07 to 3.20, depending on the relative proportions of its various constituents. Also diagnostic is the crosshatched color pattern, which is the result of the mineral's internal twin.

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5 GUATEMAL JADE — FOSHAG 29Prehnite.-This silicate mineral of limeandaluminum, sometimes Prehnite.-This silicate mineral of limeandaluminum is sometimes found among the nephrites of Mexico, but has not yet been found in Guatemala. A common diagnostic feature is the presence of small metallic pieces of native copper embedded in the ore. It is now widely used in the production of fraudulent antiques to sell to tourists in Chichicastenango and other centers.

Some of the nicest colors are olive green, calla green, cedar green, ivy green, grape green or lime green, also bone brown to black. Its use is mainly limited to beads and poorly executed figurines, except in Mexico where Olmec figures of high artistic merit are found in this material. Numerous beads of this mineral, from Quiche, are found in the Rossbach collection, being among the commonest materials.

Usually, objects made from this variety of serpentine are roughly executed, except for the fine Olmec figurines of Mexico, which are sometimes in this variety of serpentine.

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PHYSICAL PROPERTIES OF JADEITE AND JADELIKE MINERALS The usual method of distinguishing jadeite and differentiating it

LOCAL CHARACTERISTICS

5 GUATEMALAN JADE — FOSHAG 37 Early and Late Classic material and celts of this material recovered Early and Late Classic material and celts of this material recovered from archaeological sites are still used by present-day potters in Guatemala. Some of the local characteristics of the hard stones used will be given in the following notes. Extensive excavations were carried out here by the Carnegie Institution of Washington, the results of which have been reported by Riketson and Riketson (1937).

Considering the number of graves encountered during these excavations and the abundant supply they contained, the amount of jade found was small and the quality of the material poor. That a lack of appreciation of this stone was not the cause of this scarcity of material is shown by the careful re-use of material, such as the fitting of almost insignificant fragments of richly colored mineral and cut beads into mosaics (447, 449). . The mural discovered in Building B-XIII by the Carnegie Institution shows a simple use of ornaments, earplugs, nose ornaments, necklaces and.

Its main use was in mosaics, where it is clearly recycled material, extracted from beads and earplugs, or carved cabachons.

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None of the other Guatemalan collections compare to the Kaminaljuyu material due to the high proportion of fine stone. Particularly striking are the large numbers of objects from fine apple green to emerald green jadeite (type I). The light green jade (type III) is also better colored and brighter than comparable jade from other sites.

Fine apple-green jadeite, similar in appearance to the green jadeite from Burma, makes up half of the jades in the collection. Type III jade, common assemblages from the Quichen, are similar but have a waxy rather than glassy luster and rarely show the distinct granularity of the Kaminaljuyu stone. Jade of type IV, a dense white stone mottled with greenish gray color is represented by six examples, the most characteristic of which.

Metadiorite is represented by six objects, four of which are crude earplugs of similar material.

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In addition to jade, the collection contains objects in serpentine, jasper, zoisite, steatite, albite, muscovite, calcite-jasper and metadio-. In stone, the Patzun-Godinez material shows strong affinities with the general collections from Quiche. This is especially true of the relative abundance of pale green sea jade (type III).

Quiche (Rossbach Collection).— The Rossbach Collection was assembled by the former parochial priest, Father Rossbach, of Chichecastenango, and is now housed in a small public museum in that town. The Quiche material, as illustrated by the material in this collection, shows a wide variety of jade, usually of poor quality, and an abundance of lesser stones. This should perhaps not be considered characteristic of the material of the area, but of the variety of stones used in minor objects.

Of the characteristic and recognizable types, the pale green variety (type III) is the most abundant.

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5 GUATEMALAN JADE — FOSHAG 43 Smaller objects, besides those of jade, include a wide variety. Smaller objects, in addition to those of jade, include a wide variety of materials: serpentine, muscovite, amazonstone, actinolite, steatite, metadiorite, jasper, jasper-calcite, marble, andalbite. The pale green stone without obvious granularity (type III,b), which is not represented in the Kaminaljuyu jades, is. 52 percent of the samples cannot be readily assigned to any type of jade.

Three small broken fragments of aquamarine, pale blue to pale green in color, are the only examples of this mineral found in Guatemalan collections. In the large percentage of light green jade (type III) and the large proportion of miscellaneous stones among the small objects, this collection has strong similarities with the collections of the Quiche.

LAPIDARY TECHNIQUES

NO. 5 GUATEMALAN JADE — FOSHAG 45 from the dictionary of Molina (1585) and grammatical construction

And it is broken by striking with a stone

NOTES

NO. 5 GUATEMALAN JADE — FOSHAG 49

Pedernal, or piedra recia, is flint (hd. 7), or any hard stone, which, if crushed into fine sand or dust, would serve its purpose. Today garnet is often used as an abrasive, due to its sharp lunate fracture it is particularly useful for processing iron and. Of these minerals, alumina, quartz, augite, chert, olivine, biotite, and magnetite are common constituents of the volcanic ash that blankets the region around Kaminaljuyu. The pure nature of this sand suggests that it is.

Material such as this sand can serve satisfactorily for sawing, grinding and polishing jade when used with a metal or. Beryl (hardness 8) is a useful abrasive and was known to the indigenous people of the region, but it is a very local mineral.

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Sawing in this way was a quite ancient feat, as this is evident from some mosaic pieces of a Miraflores headdress from Kaminaljuyu. Large objects were drilled in the same way; the junction of the two holes, unless reamed out, shows a thin broken septum. Both objects were drilled twice, first from one side and then from the other, so that they met so perfectly in the center of the stone that the joint is barely noticeable.

A remnant of the cutting groove at the bottom of the core indicates a cutting edge of the drill, if mm. The ratio of internal diameter to thickness of the bore walls is usually about 5-6:i, but sometimes varied widely. The nicely chamfered edge of the horizontally extended ear tips was certainly made this way.

Plate i, figure 2, e, is almost certainly a reamer and fits well with the wide throat of some of the ear-plugs.

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5 GUATEMALAN JADE — FOSHAG 57produced in this way, as well as headbands and the demarcation produced in this way, as well as headbands and the demarcation of the headdress. Finer details can be provided with fine-pointed jadeite rods, such as one from Mexico in the collections of the U. Great Celts, such as that shown in plate i, figure 2, /, would serve for roughening the larger elements of some designs.

String sawing.— A specimen from Nebaj (4760), depicting a turkey (?), shows large comma-like elements in the design, which possibly

PLATES

Jade working tool, a, Jade, drilled hole with central pointed core, Nottebohm collection; b, chloromelanite clearer, Nottebohm collection; c, chloromelanite reamer and polisher(?), Nottebohm collection; D.