Today, we return to the path of genuine minerals. Still, it’s not the main road, but a bit of a detour, or perhaps better put, one of the long and winding scenic routes, one marked by small feathery branches leading off in all directions. It’s not a spectacularly expensive journey, but one that is highly unusual, and confined to a relatively small part of Indian Country.
This week’s featured gem is an unusual stone, one found (so far as is known at this point) in only one area: Montana moss agate. Frequently, it doesn’t even look like agate, particularly in smaller cabochon form. For those unfamiliar with the gem, it’s probably easy to mistake it for a jelly opal with highly irregular inclusions, or even for a “stone” that is entirely synthetic, made of polymers and artificial substances. Its look, at least for those of us with various forms of synesthesia, gives it a seeming “feel” that is not especially mineral-like.
We’ll get to moss agate generally, and the Montana variant specifically, in a few moments. First, let’s revisit the mineralogical and other properties of its parent category, agate itself.
We’ve looked at agate here before, on more than one occasion. Rather than paraphrase myself, I’ll simply quote here what I wrote originally to explain agate’s mineralogical properties:
Agate is, essentially, one stone with seemingly infinite variations — with, predictably, a caveat or two. There are a couple of other stones that straddle the boundary between agate and some other mineral, and because of the process by which agate forms, it is also possible for entirely different minerals to take on some of its properties (i.e., becoming agatized). Don’t worry; we’ll separate all the strands of stone here.
First, what agate is: Agate is a cryptocrystalline form of silica, which is commonly known (in this context) as quartz. We’ve looked at quartz here before (and, indeed, agate itself, to a limited extent). The descriptor “cryptocrystalline” denotes the size and type of crystal structure: In the case of agate, the crystals are so small — indeed, so truly microscopic — that they appear invisible except via powerful magnification under polarized light. Thanks to this minute structure, some sources refer to this variety of quartz as microcrystalline.
. . .
Agate is nearly always a part of one specific family of quartz known as chalcedony (another mineral that we’ve explored here, too). As is usually the case, however, there are no absolutes. One of the requisite features of agate is its banding patterns (which, depending on the size of the bands relative to the size of the individual stones, may not always be visible as bands). Occasionally, minerals such as carnelian will manifest in such banding patterns; some mineralogists classify these particular variants as both carnelian and agate. Similarly, some forms of onyx, particularly sardonyx, will develop bands that permit some to classify them as part of the agate family. And, as noted above, occasionally another mineral entirely (or even another non-mineral substance, such as petrified or fossilized wood, or fossilized dinosaur bone) will be subjected to agatizing processes.
At the same time, we also looked at how agate is formed:
Clearly, key to agate’s identity is how it is formed, and that is indeed what makes the stone what it is. It’s a type of stone common to beds of volcanic and metamorphic rock, where heat and pressure combine to alter existing geologic strata and transform one or more substances into something new (and, frequently, something very, very beautiful). Often, creation occurs as the product of both volcanic and metamorphic processes: When molten lava or other volcanic masses harden, they will often develop cavities (e.g., as a result of water or of air or gas bubbles); over eons, the shifting and pressure of metamorphic processes forces nearby silicates into the cavities in a process much like pseudomorphism, which we’ve discussed several times. The silicate materials are extruded into the cavities over extended periods of geologic time, meaning that they form in layers; this is what creates the banding effect. Eventually, the volcanic material shatters under the pressure, or simply crumbles into dust over the span of millennia, exposing the agate material to view.
The broader category of moss agate, of which the Montana variant is only a subset, looks very different, generally speaking. It also often does not look especially like agate, at least as the mineral si usually conceived. Agate’s hallmark is its banding, the presence of nested rows and lines in a a shared pattern. Moss agate, by contrast, often possesses a matrix more like what one would expect to find in turquoise or many other stones: thin traceries of lines, spiderwebbed or merely scattered throughout the stone, or blockier patches and swatches and droplet-like patterns. The absence of banding leads some sources to conclude that moss agate is not a true agate, but the label has now stuck.
Moss agate also tends to manifest in shades of green and white, with the stone itself usually whitish and the matrix a deep forest (or mossy) green, part of what gives the stone its name. (The name also derives, in part, from the fact that matrix often has a feathery, mossy look to it; sometimes it is simply an unusual formation of the mineral lines themselves, but sometimes it is due to the presence of dendrites, which we’ll cover in a moment.) The bright green hue is usually due to the presence of such minerals as chlorite or hornblende, although sometimes the matrix comes from manganese, and appears brownish to blackish in color.
Montana moss agate belongs in this latter category of color, with some caveats, of course. If you look at the Wikipedia page for moss agate, at least as of this writing, the second image on the right sidebar is of a large piece of Montana moss agate. In that particular stone, traditional banded agate patterns lie in the stone’s center — the center, roughly speaking, in both area and depth. What encircles that banded section, and, if you look closely, what covers it, is a translucent layer of mineral on the white-beige-pink spectrum, one filled with numerous, irregular, and very unusual separate inclusions. Those inclusions are dendrites, delicately branched and feathery bits of mineral — in this case, usually iron and manganese oxides. Some dendrites were once living creatures whose beings were captured in stone and replaced, over eons, by minerals (a process known as pseudomorphism, which we’ve covered here many times before). However, many are simply bits of mineral that, crystallizing over stretches of geologic time and under intense pressure and heat, have simply spread into delicate branching formations within the host rock. Indeed, the word dendrite comes from neurology, and refers to the branched endings of nerve cells that transmit and receive neuronal impulses. Even where it refers to entirely inorganic material, the term pays tribute both to its resemblance to something living and to the act of its formation.
In gemwork, most of the cabochons cut from Montana moss agate tend to be of this translucent dendritic material. I have seen cabochons and slabs only rarely that include the banding; for most cutters and cabbers, the point of using the stone lies in the unusual and gel-like appearance of its non-banded areas.
Moss agate is found all over the world; I’ve seen specimens online with labels sourced to Africa and South Asia, among other points on the globe. It’s found in some areas of Europe, and in Australia. So far, I’ve tracked down only one source in South America, in Argentina, but deposits exist all over North America, from Canada to Mexico. Here in this country, it’s found all over the continental United States, with several reported deposits right here in New Mexico. Montana moss agate, however, is so named because it is found (at least as far as is known at the moment) only in one region of Montana: in gravel deposits along the Yellowstone River and its tributaries, a region spanning several counties in the state. Interestingly, its name derives from the place where the stone is found, and not the place where it is thought have been formed in the first place, which is in Yellowstone National Park in Wyoming: Geologists believe that it was formed in the volcanic areas of what is now the park, and washed out along the Yellowstone River to rest in alluvial deposits in Montana.
It would not surprise me to learn that, to the Native peoples indigenous to the Yellowstone area, what is now called Montana moss agate might have had cultural significance. If it did, it might have been spiritual in nature, yes, but it might also have been simply artistic, used as adornment. Now, however, the Internet is rife with “New Age” crystal practitioners who have invented all sorts of supposedly “Native ” symbolism for the stone. One in New Zealand connects it to childbirth and “new beginnings”; one in the U.K. projects all sorts of “powers” onto it, from healing to healthy relationships to purifying to preventing dehydration to a supposed role as a bringer of rain to unspecified “Native Americans”; one in Montana calls it a Native “warrior stone,” accompanying the description with an appropriated photo of Sitting Bull. It’s doubtful that there;s a single grain of truth to any of the allegedly “Native” descriptions in any of them; if it was (or even still is) used by any of the indigenous peoples of the area, the truth of its use would no doubt be simultaneously far more simple and far more complex.
For Wings, it’s simply a unique gift of the earth, highly unusual and unusually beautiful, one that evokes images of living beings captured forever for the historical record and thereby remembered, as they should be. It’s no surprise, then, that the two pieces he’s made thus far with this singular jewel have been in the form of Turtle: the Grandmother who holds our world on her back. The necklace shown at the top of this post was one he created about five years ago, and in a bit of a departure from his usual style: This turtle had fully articulated legs. I sold her to an older woman who used a wheelchair; she and her husband were visiting from Michigan, and the stone’s singular appearance and power caught her attention and refused to let go. She wore it out of the gallery. The second, smaller turtle shown here was a pin, one made for a very special and much-loved client for whom Turtle has always had very personal significance. At the moment, Wings has only none of this mysterious stone in his current inventory. We do, however, have a couple of established sources for acquiring more, should it speak to you.
And speaking is, I suspect, part of the stone’s attraction: Unlike its more opaque counterparts, it lifts the veil, allowing us to see directly into its interior to the other minerals and materials that make it so very much more than the sum of its parts. It allows us a chance to hear a voice from long ago, many voices raised in harmony, each element relating the story of what it once was, and what it has become. It is the voice of the stone’s collective spirit, one with many delicate branches to animate it.
~ Aji
All content, including photos and text, are copyright Wings and Aji, 2015; all rights reserved. Nothing herein may used or reproduced in any form without the express written permission of the owners.
