Turquoise Locations

When I reached the bottom of the mountain, the landscape changed abruptly. The mountain shifted steeply from sheer cliff to flat desert. At this point, I typically look for a spot to leap down the last few feet. However, this time I was tired and thirsty. So, I sat down to drink a bottle of water and acclimate my eyes to the harsh sunlight.

After a few minutes, I looked down at the ground. I couldn’t believe what I saw. Right between my feet lay a beautiful 8-carat turquoise gemstone devoid of most of its host rock. I picked it up and admired its beauty. The stone was shaped like a small egg with a mottled blue and white pattern. Since the desert was mostly shades of tan and brown, the stone really stood out. In the flats, the color of the sand varies very little. Therefore, you can easily pick out surface deposits of different minerals, like magnetite and copper, while hiking. Only when exploring the mountains do you see the different layers of mineral deposits, due to erosion.

. . .

As I surveyed the land around me, I realized I sat in the middle of an exposed turquoise deposit. All around me lay blue stones of all shapes and sizes. I found turquoise ranging in size from the head of a pin to two hundred carats. Their shapes varied from round to oval. Some were elongated. I always carry a plastic bag with me, so I walked around and filled it with blue stones.

In the months since that fateful day, I’ve found four new deposits. Each one incorporates a slightly different hue of turquoise. Some specimens are so soft you can scratch them with a fingernail. Others are so hard you can barely scratch them with a pen knife. I’ve found turquoise stones in different shades of blue as well as green.

ARIZONA TURQUOISE DEPOSITS

The Turquoise District

Location: The principal turquoise deposits, for which the district was named, are located about three-fourths of a mile northwest of Courtland, immediately west of the top of Turquoise Ridge. There are also many minor showings of the mineral along the entire length of the west flank of that ridge.

Geology: Post-Lower Cretaceous granite here underlies, with intrusive contact. Bolsa quartzite that strikes about N. 10° W., and dips from 55° to 75° eastward. Along the plane of intrusion, some slight schistosity and visible alteration to kaolin and sericite have been developed. A few minor faults and frequent prominent fractures, of ages both earlier and later than the turquoise, traverse these rocks in various directions.

Features of occurrence: The turquoise occurs mainly as thin, pinching stringers up to a few inches wide, and small, nugget-like lenses, occupying joints and fractures in the quartzite and in the granite. Associated with the turquoise, generally between it and the walls of the stringers or veinlets, are kaolin, sericite, and limonite. The widest stringers of turquoise extend out from intersections of fractures transverse to the granite-quartzite contact with fractures parallel to the quartzite bedding. The best quality of material is found in the quartzite, within a few feet from the granite. The turquoise in the granite, and whenever associated with abundant limonite, tends to be too soft and green, due to too high a copper content. Nothing concerning the continuity of the turquoise with depth could be ascertained from the comparatively shallow workings within its deposits.

Origin: To form turquoise, certain compounds of phosphorus, aluminum, copper, oxygen, and water must be brought together under suitable conditions. The fact that the turquoise in this district is limited to the quartzite-granite contact indicates that the granite had something to do with its origin. The phosphorus required may have been derived from the mineral apatite, which is present in the granite. The small amount of copper necessary may have been present in the quartzite, migrated in from the Abrigo limestone, or been derived from the granite. Aluminum may have come from any of the rocks. The bringing together of these compounds in proper proportions and the depositing of them as turquoise in the quartzite and granite could have been accomplished in various ways. Either normal ground water circulation, ground water heated by the granite intrusion, or hot solutions emanating from the parent granite mass during its solidification could have been the agency. The association of sericite with the mineral strongly suggests a hydrothermal origin.

Sericite is a fine grained mica, similar to muscovite, illite, or paragonite. Sericite is a common alteration mineral of orthoclase or plagioclase feldspars in areas that have been subjected to hydrothermal alteration typically associated with copper, tin, or other hydrothermal ore deposits.

A Pb-Ag-Au-Cu-Zn-Mn-Quartzite-Turquoise mining district located in T.19, 20S., R.24, 25E. This District is located about 18 miles NE of Tombstone and 20 miles north of Bisbee. It occupies an area about 4 miles long from north to south by 2 miles wide in the southeastern margin of the Dragoon Mountains.

The principal features of relief are two ridges of NNW-ward trend, fringed on the east by low foothills. The northern, Turquoise Ridge, is separated from the southern, Gleeson Ridge, by a narrow gulch. These ridges are each about 2 miles long by less than a mile wide, and they rise 900 to 1,200 feet above the adjacent plains.

The structure at Gleeson and Courtland is highly complex due to faulting and igneous intrusions.

Quartz monzonite and quartz-monzonite porphyry intrude the Paleozoic and older rocks but were not found affecting the Cretaceous. Granite and felsite cut the monzonites, and the granite invades the Cretaceous beds.

The strata of Turquoise and Gleeson ridges predominantly strike between N. and N30ºE., and dip steeply eastward, but locally they show considerable variations in altitude.

Steeply dipping faults of general northerly and easterly trends are common in the district. Movement on them has been both vertical and horizontal, and locally they displace the low-angle faults.

Mineralization is of several types: (1) Copper carbonates and oxides in irregular blanket deposits where Cambrian Bolsa Quartzite and Abrigo Limestone are thrusted over Carboniferous limestone; copper sulfides, oxides, and carbonates in irregular replacement deposits in Cambrian Abrigo Limestone; and copper sulfides, oxides and carbonates in irregular, tabular, pyritic lenses in Carboniferous limestone along, or close to, a contact with quartz monzonite intrusive; (2) Lead and zinc carbonates, lead sulphate, and zinc silicate with silver chloride, manganese and minor copper and gold in irregular orebodies in Pennsylvanian-Permian Naco Group limestones along, and at intersections of, fractures and faults; (3) Turquoise in near-surface stringers and lenses in altered granite and quartzite; (4) Manganese oxides in irregular bunches, lenses and masses along fractures in limestone; and (5) Spotty and weak base metal ores with gold and silver values in veins in intrusive rocks.

Workings include numerous mines and prospects developed by shafts, tunnels and adits since 1883. At least 887,000 tons of base metal ore and some 250 tons of manganese ore were produced plus some turquoise and a considerable production of quartzite smelter flux.