University of Virginia Library

Mineral:

The minerals and rocks utilized prehistorically in the Chaco
Canyon constitute a list of considerable length. The archaeologic record
probably coincides fairly closely with the actual list, excepting in the
pigments and hydrocarbons. There follows a complete list of minerals
recovered from Chaco excavations:[19]

• Agate (SiO2)—A variegated chalcedony form of quartz. Both banded
  and moss agates have been found in Chaco ruins. Unworked. Probably
  derived from silicified logs in Kirtland shale and Ojo Alamo
  conglomeratic sandstone.

• Alabaster (CaSO4. 2H2O)—A fine-grained, sub-translucent variety of
  gypsum. Possibly obtained from the Mesaverde group or the Kirtland
  shale, but more probably brought in from eastern deposits
  near the Nacimiento uplift or along the lower Rio San Jose.

• Albatite (sic)—Reported from Chetro Ketl. No further data. Possibly
  albertite or albite.

• Aragonite (CaCO3)—Same chemical composition as calcite but crystallizes
  in the orthorhombic system, and is harder. Use unknown.
  Possibly from Lewis shale, but more probably from the Kirtland
  shale, from fossil shells, and from the Puerco and Torrejon formations.

• Argillite—A schist or slate derived from clay. Pipes of argillite were
  found at Tseh So. Probably derived from argillaceous shale beds
  in the Allison member, or from the Lewis or Kirtland shales.

• Azurite (2CuCO3. Cu (OH)2)—A blue carbonate of copper. Frequently
  found in Chaco ruins unworked, in beads, and powdered
  for pigment. Probably derived from the Zuñi mountains, or from
  

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  isolated patches in the Navajo (old usage) sandstone in the Dutton
  plateau.

• Basalt—A dense, fine-grained dark-colored igneous rock containing
  much hornblende. Used for percussion and grinding tools, but not
  common. Possibly brought in from the river terrace deposits along
  northern tributaries of the San Juan, or from the lava flows north
  of Bluewater, some fifty miles south of the Chaco.

• Calcareous tufa (CaCO3)—A redeposited limestone form of calcite.
  So far in the Chaco, found only in the Chetro Ketl excavations.
  Used for beads. Calcareous rocks are rare in the Chaco area, but
  the Lewis shale contains some thin layers of impure limestone
  which may have contributed to the formation of tufa.

• Calcite crystals (CaCO3)—A crystalline form of calcium carbonate,
  found rather commonly in Chaco ruins. Used for beads and pendants.
  Calcite crystals are found in bedding planes in the Puerco
  formation.

• Cannel coal—Commonly considered to be a compact variety of bituminous
  coal, although it averages less fixed carbon and more volatile
  material. Possesses dull luster and conchoidal fracture. Used for
  beads. No deposits of cannel coal have been reported from the
  Chaco area, but possibly small lenses occur in the predominant
  sub-bituminous seams. The identification may have been erroneous,
  instead of jet or lignite.

• Carbonaceous shale—Altered clay beds containing considerable brownish
  bituminous material. Quite common in the Chaco Canyon, especially
  in the upper portion of the Allison member. Used for
  flooring, etc., in pueblo construction, and for pot covers, ornaments,
  etc.

• Chalcedony (SiO2)—A light-colored cryptocrystalline variety of quartz,
  transparent to translucent, and with a waxy luster. Agate and
  onyx are forms of chalcedony. Found commonly as material for
  scrapers, knives, projectile points, polishing stones, hammer stones,
  etc. After sandstone, chalcedony and chert were the minerals
  most commonly used for artifacts in the Chaco area. Probably
  derived from silicified logs in the area, and pebbles in the Ojo
  Alamo, Puerco, and Torrejon formations.

• Chalk (CaCO3)—A soft, whitish compact limestone form of calcite.
  Reported from Pueblo Bonito. No chalk beds are known in the
  Chaco, but there may be small deposits in the Lewis shale.

• Chert (SiO2)—An impure, brittle, usually grayish-colored quartz.
  Chert is sometimes called hornstone; also the term chert is often
  applied to any impure flinty rock, including jaspers. The usage
  of the term in archaeologic reports is uncertain. Used for artifacts
  

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  in the same manner as chalcedony. Pebbles of gray, brown,
  and black chert are found in the nearby Morrison, Ojo Alamo, and
  Torrejon formations; but possibly much of the chert used in the
  Chaco area (and all over northern New Mexico) came from the
  prehistoric quarries on the flank of the Cerro Pedernal in the
  Chama drainage.

• Clay—Earthy material, plastic when wet, composed chiefly of hydrous
  aluminous silicates. Most of the clays in the Chaco Canyon are
  recent alluvial (in the valley fill), and argillaceous shales. Principally
  in the upper portion of the Allison member, and to a minor
  extent in the Chacra sandstone, are thin stringers of hard white
  clay interbedded with lignite and sandstone. Experiments with
  this clay indicate that it is identical with most, if not all, of the
  clay used by the prehistoric inhabitants of the Chaco in making
  their ceramics. This same clay was utilized in making much of
  the plaster used in the pueblos, both in a pure form and mixed with
  caliche (a calcareous adobe or clay). The sandy alluvial clay or
  adobe, found exposed in the Chaco channel walls, was used for
  plaster, mortar, and wall fill. Beads and other ornaments were
  likewise made from clay.

• Copper (Cu)—The only malleable metal found in Chaco excavations.
  Bells, hammered copper, beads, and nuggets have been found in
  Pueblo Bonito and in Chetro Ketl. Although native copper is found
  as close as in the Zuñi Mountains and in Rio Arriba county, there
  is no evidence that it was mined prehistorically in New Mexico. The
  general supposition is that the raw and worked copper items were
  traded up from the south, possibly from Durango or Zacatecas in
  Mexico.

• Diabase—A fine-textured dark-colored igneous rock; actually a general
  and collective term applied to fine-grained varieties of dolerite,
  gabbro, and diorite. Used to a minor extent for instruments of
  percussion, etc. Probably brought in from the area north of the
  San Juan river.

• Diorite—A dark-colored igneous rock with medium or coarse grains.
  Used infrequently for cutting blades, percussion tools, etc. Also
  probably derived from the river terrace pebbles to the north.

• Flint (SiO2)—A semi-translucent gray to black quartz with a pronounced
  conchoidal fracture. The term has been used quite
  loosely, and probably the items so identified were of chert. True
  flint is not known from the Chaco area, nor from Northwestern
  New Mexico at all, according to the definition of flint accepted by
  many mineralogists.

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• Galena crystals (PbS)—A lead sulphide, the commonest of the lead
  minerals. Found in two Chaco Canyon excavations, unworked. In
  the Zuñi Mountains and in Rio Arriba county are the nearest
  sources.

• Garnet—This term is applied to the members of a varied group of
  metallic silicates. Garnet has been reported only from the Pueblo
  Bonito excavations, and was probably the pyrope or blood-red
  precious garnet. These are obtained from ant hills, etc., in the
  vicinity of Fort Defiance, Arizona, and elsewhere as in Buell Park,
  and Garnet Ridge on the Utah-Arizona line.

• Gilsonite or Uintahite—A brittle variety of asphalt, lustrous black in
  color, with a conchoidal fracture. Probably the same as manjak.
  Found in Utah, and western Colorado, and in veins in sandstone
  strata southwest of Aztec. It superficially resembles another
  asphalt (wurtzilite), and has frequently been confused with the
  jet variety of lignite. Usually employed for ornaments, inlays,
  and "buttons."

• Gneiss—Commonly a metamorphosed granite of a light color. The
  nearest source is in the conglomeratic Ojo Alamo sandstone. So
  far found only in one Chaco ruin, in instruments of percussion.
  Possibly brought in from the Garnet Ridge area.

• Goethite (Fe2O3. H2O)—A hydrated iron oxide resembling limonite.
  Found in Pueblo Bonito. Probably found with other oxides of iron
  in the area.

• Granitic rocks—A group of medium-fine to coarse-grained plutonic
  acidic igneous rocks, normally light colored. A few manos at Tseh
  So are of granite. Probably derived from the Ojo Alamo conglomerate.

• Gypsum (CaSO4. 2H2O)—A hydrous calcium sulphate found in several
  forms including alabaster, selenite, and rock-gypsum. Found commonly
  in the Chaco ruins, used in plaster, and for beads, pendants,
  tablets, etc. These uses refer to the rock- or plaster-gypsum.
  Gypsum is found scattered through the Mesaverde group, but is
  more abundant in the Kirtland shale.

• Hematite (Fe2O3)—An iron oxide. Occurs commonly in the argillaceous
  and fossil concretion forms, and less commonly in the earthy or
  red ochre form, throughout the Chaco area. Polished cylinders
  of problematic use, concave concretions used as mortars, beads,
  and other varied forms are found commonly in Chaco ruins. Usually
  when an archaeologist reports "hematite," he is referring to
  the non-earthy forms. (See Iron Concretions, and Red Ochre.)

• Iron concretions—Term loosely employed for various concretions,
  usually of hematite, in the Chaco area.

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• Iron pyrites or pyrite (FeS2)—This pale brass-yellow "fool's gold" is
  an iron sulphide. Occasionally it is found unworked in Chaco
  ruins. It occurs sporadically as concretions in the local coal seams;
  and is found both in crystalline and massive form in the Chacra
  sandstone. It is possible that some of the pyrite reported by archaeologists
  may be marcasite.

• Jasper (SiO2)—An opaque massive quartz, usually red, brown, or
  yellow in color. Used rather commonly for projectile points and
  ornaments. Derived from silicified logs, and from pebbles in the
  Ojo Alamo conglomeratic sandstone. Possibly some of the jasper
  may be a product of the burning coal beds of the Chaco area which
  have baked clays and shales into porcelain jasper.

• Jet—A "jet black" variety of brown coal or lignite. It is a compact
  hydrocarbon, takes a high polish, and has a conchoidal fracture.
  Used for beads, "buttons," inlays, and various other small carved
  items. There may be some confusion in the identification of items
  listed by archaeologists as jet, lignite, and gilsonite. Probably
  derived from the coal seams in the Chaco Canyon.

• Kaolin—A white residual and sedimentary clay composed chiefly of
  kaolinite. Pieces of raw kaolin have been reported from two Chaco
  ruins. It is quite possible that these identifications were in error,
  as the clays of the San Juan area are chiefly clay shales, plastic
  clays, and fire clays.

• Lignite—A variable variety of coal, ordinarily brown in color and
  ligneous in texture, which checks irregularly and breaks into thin
  slabs. The black form of lignite is known as sub-bituminous coal.
  This is the dominant type in the Allison and Chacra members of
  the Mesaverde. In 1905 R. Wetherill opened up a mine, one mile
  west of Pueblo Bonito, in the upper portion of the Allison where
  five feet of coal seams were exposed. There is no evidence that
  the prehistoric dwellers of the Chaco Canyon ever deliberately used
  coal as a fuel, although carbonaceous shale was used as a flooring
  material, and various ornaments of lignite have been recovered.
  It should be mentioned, however, that in August of 1936, Dr.
  Ernst Antevs and the writer noted fragments of lignite concentrated
  in the fire pits of several pit houses which had been exposed
  by the collapse of a section of the Chaco river bank near Shabik'eshchee.

• Limestone (CaCO3)—A variety of calcite. Occasionally found in Chaco
  ruins, worked into tablets or palettes, and beads. Possibly derived
  from the layers of impure limestone in the Lewis shale, but more
  probably from Lower Cretaceous rocks in the Dutton plateau to
  the south.

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• Limonite—Commonly a mixture of several hydrated iron oxides, usually
  found in amorphous, concretionary, and earthy forms. Both unworked
  concretions, and earthy limonite (yellow ochre) are found
  in Chaco ruins. Derived from various rocks throughout the Chaco
  area.

• Malachite (CuCO3. Cu (OH)2)—A green carbonate of copper. Found
  unworked, and ground for pigment. Occurrence same as that of
  azurite.

• Mica—A group of minerals, including muscovite or "isinglass" and
  biotite or black mica. Mica sheets have been reported from Pueblo
  Bonito. Probably obtained from Rio Arriba county.

• Monzonite porphyry—A fine to medium grained group of igneous rocks
  with a porphyritic texture. Used at Tseh So for instruments of
  percussion. Possibly derived from the Ojo Alamo conglomeratic
  sandstone.

• Obsidian—Volcanic glass, with a decided conchoidal fracture, commonly
  black in color. Fairly common as a material for projectile
  points. Possibly derived from pebbles in the Ojo Alamo sandstone,
  but more probably obtained from the Jemez—Cerro Pedernal
  area where a stream known as Obsidian creek contains numerous
  nodules or pebbles of this material.

• Ochre, red (Fe2O3)—The earthy or rouge form of hematite. Used as
  a pigment. Found sporadically over the Chaco area in sandstones
  and shales.

• Ochre, yellow (2Fe2O3. 3H2O)—The earthy form of limonite. Used as
  a pigment. Found scattered over the Chaco area, especially near
  Pueblo Alto. At present yellow ochre is worked commercially
  near Farmington.

• Onyx (SiO2)—A horizontally banded form of agate or variegated chalcedony.
  Found as beads at Chetro Ketl. Probably derived from
  the Kirtland shale, Ojo Alamo sandstone, and Puerco and Torrejon
  formations.

• Petrified or silicified wood—Woody material replaced normally by silica
  to constitute psuedomorphs after wood containing agate, amethyst,
  chalcedony, jasper, opal, onyx, and quartz. Commonly used for
  arrowheads and instruments of percussion. Fragments and logs
  of petrified wood are frequently found in the Kirtland shale and
  Ojo Alamo sandstone.

• Picrolite (H4Mg3Si2O9)—A variety of serpentine with long coarse
  fibers, not easily separated nor flexible. Reported from Chetro
  Ketl in beads. Possibly obtained from the Garnet Ridge area,
  Arizona-Utah, or from Rio Arriba or Catron counties.

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• Pumice—A cellular form of volcanic glass. Reported from Pueblo
  Bonito. Probably derived from the area immediately southwest of
  Mount Taylor, where pumice deposits have been worked commercially
  in recent times.

• Quartz (SiO2)—The dioxide of silicon, possessing a large number of
  distinct varieties. In addition to sandstone, quartzite, petrified
  wood, onyx, jasper, flint, chert, chalcedony, and agate—discussed
  separately—rock crystal, and milky or vein quartz, have been
  found in Chaco ruins. Probably derived from the Ojo Alamo
  sandstone and from the Puerco and Torrejon formations.

• Quartzite—Metamorphosed silicaceous sandstone. Used for percussion
  instruments. Probably obtained from pebbles in the Ojo Alamo
  conglomeratic sandstone.

• Reddle—A clay and red ochre mixture resembling argillite, but softer.
  Found as beads at Tseh So. Probably obtained from local shales.

• Rhyolite—A dense, fine-grained, light-colored volcanic rock, constituting
  a variety of felsite. Used for hoes at Tseh So. Probably
  derived from the Ojo Alamo sandstone, or brought in from the east.

• Sandstone—A rock composed of grains of sand, usually of quartz.
  The dominant rock in the Chaco area where the cementing material
  is usually calcite and iron oxides. Sandstone was by far the most
  important non-organic material utilized by the prehistoric inhabitants
  of the Chaco. It was the chief component of the masonry
  houses; most of the metates, manos, and mortars were of sandstone;
  also, trays, palettes, disks, sandal lasts, and many other
  artifacts were made of sandstone. Pictographs were painted on
  sandstone walls, and petroglyphs were carved over thousands of
  square feet of canyon wall and sandstone boulder. Bedrock as well
  as fragments were used as rasps, grindstones, and knife sharpeners.

• Selenite (CaSO4. 2H2O)—A transparent cleavable crystalline variety
  of gypsum. Unworked fragments of various sizes have been found
  in Chaco ruins; also worked as ornaments. It may possibly have
  been used in windows, as later Pueblo peoples have utilized the
  larger crystals. Selenite is found sporadically throughout the
  canyon, and there is a stratum in the cliff just back of Tseh So.
  Should selenite have been used as a window material, possibly
  sufficiently large crystals were brought in from the area south of
  the Mesa Lucero and west of the Rio Puerco of the East.

• Serpentine (H4Mg3Si2O9)—A non-crystalline massive mineral of various
  shades of green. Reported at Chetro Ketl in beads. Possibly
  from northern Arizona, or from Rio Arriba or Catron counties.

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• Shale—A soft sedimentary rock, with normally a thinly laminated
  structure, formed by the consolidation of beds of mud, clay, or silt.
  In the Chaco area the shales are only less important than the sandstones.
  Gray, green, brown, and black shales are most common, the
  black to gray carbonaceous shales being preponderant. Shale was
  used as floor material, for beads and other ornaments, olla lids
  or covers, tablets and palettes, etc. Archaeologic reports normally
  do not differentiate among the shales, but some reports list specifically:
  argillaceous shale, green shale, carbonaceous shale, ferruginous
  shale, and siltstone. Siltstone is merely a quite soft shale
  lacking in quartz particles.

• Steatite or soapstone (H2Mg3Si4O12)—A compact gray to green form
  of talc. Reported from Pueblo Bonito as a coarse green steatite.
  This may be a talc-schist. Possibly obtained from the Garnet
  Ridge area or from Rio Arriba county.

• Sulphur (S)—A yellow non-metallic element. Reported from Pueblo
  Bonito as native sulphur. Distributed in small quantities throughout
  much of the Chaco area, especially in the shales and coal seams.

• Talc (H2Mg3Si4O12)—The foliated form, as distinguished from the
  massive steatite, is often referred to as talc. Reported from
  Shabik'eshchee. Provenience the same as for steatite.

• Trachyte—A variety of felsite superficially closely resembling rhyolite.
  Reported from Pueblo Bonito. Accompanies turquoise from the
  Cerrillos district.

• Turquoise—A basic copper aluminum phosphate. This semi-precious
  stone was and is the most prized ornament material among the Indians
  of New Mexico. It was the material most commonly used for
  beads, pendants, inlays, etc., in the Chaco ruins, as at Pueblo
  Bonito where more than 50,000 pieces and items of turquoise were
  recovered by the Hyde Expedition. Although the districts of La
  Jara, in southern Colorado, and Los Cerrillos, near Santa Fe, were
  about equally distant from the Chaco Canyon, it is commonly
  assumed that most of the Chaco turquoise came from Los Cerrillos.

In addition to the various rocks and minerals reported to date
from Chaco excavations, presumably future excavations and more
accurate identifications will provide further items—both as to minerals
and rocks, and as to uses. There are, moreover, a few minerals that
can confidently be expected from further work in Chaco ruins. Among
these are barite or heavy spar (BaSO4), used as a pigment, which is
found in the strata of the Kirtland shale; siderite or brown spar
(FeCO3), used as a pigment, and also found in the Kirtland shale; and
various metamorphic and igneous rocks (such as andesite, schist, gabbro,
slate, and olivine), which could have been picked up in the river

terraces and conglomerates of the region to the north of the Chaco.
Salt, to date, has not been recovered from Chaco excavations. Considering
its solubility, this is to be expected. Undoubtedly the prehistoric
inhabitants of the Chaco obtained salt from certain plants, and also
acquired it by trade or by special expeditions to such localities as the
Zuñi Salt Lake, and the Salinas near Willard. The present Navajo
inhabitants of the Chaco are reported to get an impure salt from a
deposit (not known to the writer) somewhere in the Escavada Wash
area. Salt also could have been obtained from saline springs which
occur in the Chaco area.