GARNETS in my Boots!

Gem-quality garnets and diopside found in anthills.

Garnets are relatively common in many places in the US. A good place to start a search for gem-quality garnets is by looking at local rockhound books and mineral and rock books in your area. These often give information on where to hunt for this gem. One way to find your own gemstone deposit, as most are overlooked by geologists (geologists are not trained to recognize gemstones, believe it or not), is to search geological maps of Precambrian terrains. The Precambrian is basically the very old rocks that form the basement for younger rocks that were later deposited on these ancient rocks. The Precambrian is designated to include rocks that are typically older than about 600 million years and may be separated into what geologists call the Proterozoic and the Archean. Don't worry too much about these designations as both may have some garnets. And the best places to find geological maps are your local state geological surveys, the US geological survey and also thesis maps in a university geology library.



Looking for gemstone garnet in anthills in Wyoming

The reason why these areas are good for hunting garnets is because these old rocks were abused by Mother Nature through geological time when placed under great pressures and temperatures causing the rocks to recrystallize. The pressures and temperatures were often favorable to crystallize garnet if the original rock had considerable aluminum. Aluminum is important as aluminum and silica are primary constituents of garent and both metals show up in mica. So look at geological maps and search for mica schists and vermiculites when looking for garnets and think of mica as an possible indicator mineral for garnet. But just because you have mica, does not mean you will have garnet, but your chances of finding garnet will increase dramatically. There will be some other rocks that contain garnet. If you are lucky, the geologist who put together the map you are looking at, may have labeled something like "garnet-muscovite schist", etc. Then there is another rock type that sometimes has garnet, but usually in localized deposits around limestone. This type of rock, may have some very nice gem garnets and other gems. The rock type is known as skarn, and can be a altered limestone or dolomite. Some of the more impressive garnets are recovered from these altered rocks. 

Next, learn to recognize garnet in rock as well as in the adjacent creek beds. A good, basic mineralogy book may be helpful in this regard. And, I'm not kidding when I suggest that anthills are great places to find gem garnets. These may be tiny garnets, but if they have clarity, they will sparkle when faceted and polished. Ants will spread out on the surface within many feet of their anthills and collect material from detritus above ground. In groups of worker ants, they will drag gems to their hills for use as ballast to protect their communes. And some companies specialize in anthill jewelry, while others just specialize in garnet jewelry, in general. 

Two of the better places that have been identified for these anthill gems include Arizona and Wyoming. Many garnets have been recovered in the four-corners region of Arizona. These are found around garnet ridge and associated with a group of lamprophyre diatremes that have erroneously been called kimberlite in the past. Some of the garnets were collected in the 19th century to provide gemstone 'salt' for the 1872 diamond hoax which took place around 'Diamond Peak' in northwestern Colorado. 

In Wyoming, excellent gem-quality garnets are found in a very large region in anthills, conglomerates, and in lamprophyre breccia pipes in Green River basin. These were initially studied by Dr. Tom McCandless while at the University of Utah, and later by the Wyoming Geological Survey. Along with garnets, many fabulous chromian diopsides are found by local rockhounds, and there are occasional diamonds found on the anthills. 

Those garnets that are transparent to translucent with few fractures can be faceted. Ugly garnets are typically industrial quality. But some opaque garnet can be cut into cabs and still produce interesting jewelry. To get garnets out of hard rock may be too much of a challenge: sometimes it is worthwhile to pan adjacent drainages in search of garnets that have naturally weathered out of the outcrop. A good example, garnets are found in outcrops at the Gore garnet mine in the Adirondacks, New York, but the best place to find detrital garnets is in nearby drainages.

While you're looking for garnet, when you stumble upon biotite, muscovite, sericite, or chlorite (mica) schist, look for garnet. If you find another type of mica schist known as vermiculite schist, look for ruby. Vermiculite schist is so silica-poor, that aluminum oxides (i.e., ruby, sapphire) are more likely to form than aluminum silicates (i.e., garnet) within these rocks. In outcrop, garnets are mostly equal dimensional, whereas ruby and sapphire form prisms (elongated in one direction) or hexagonal tabular crystals.

Garnet schist in the Elmers Rock greenstone belt.
Many dozens of garnets are visible in this photo.

Some people have a difficult time figuring out how to find gemstones and where to find them. It doesn't matter how much education or experience one has, anyone can easily mis-identify gemstones. It is important not to jump to conclusions and to focus on the physical aspects available. There are many prospectors and rock hounds I've dealt with over the years who see what they want to see and not what is really present and many tend to focus only on color. My recommendation would be to look at the shape of the mineral, any fractures, its hardness and what kind of rock one has before jumping to conclusions. In the final analysis, one may have to visit a State Geological Survey and request examination by a mineralogist or x-ray technician.

Ruby-sapphire vermiculite schist with blue kyanite

Large pink sapphire porphyroblast in vermiculite.



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Excellent rhombic dodecahedral garnets in schist from the Wrangell mine,
southeastern, Alaska

Many garnet deposits are known in Wyoming and there are even reports
of gem-quality garnets in the Hartville uplift in eastern Wyoming.
I tried to visit most of these areas, but didn't get to them all.
Those in the Hartville uplift near Guernsey still need to be investigated.
These and other garnet deposits are described in my book on gemstones.

The author receives a special award from the BLM while mapping at
South Pass, Wyoming in about 1990.