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March-April 2010

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Guest Editorial: The Mineral Preparation Dilemma—Natural Versus Aesthetic

Like the calendar year, our year with the Rogerley mine in Weardale, Northern England, has four seasons—winter is for selling (primarily at Tucson), spring is spent preparing for mining, summer is spent at the mine, and fall is spent cleaning and preparing the summer's harvest. With the arrival of our shipment from England in late September, fall officially begins, though not quite coincident with how the calendar sees it. Because operating a mine for mineral specimens does not bring in enough money to pay all the bills, everyone involved is also busy with their “day jobs” during this time, so the process of cleaning the summer's take is not as quick as it could be. Nevertheless, the last of the specimens are usually cleaned and prepared for sale by the end of November. After this, everyone gets together for a pricing party, and then the selling season begins.

Each year we send back to the United States approximately 2,500 kilograms of fluorite specimens, and, sadly, they don't come with any instruction manual on how to make them look their best. Consequently, figuring out just how to do this is a continuing and constantly evolving process. The fun of digging specimens is, perhaps, the most rewarding part of the entire procedure, but if one is to continue digging, one must make enough money from the resulting finds to pay for going back and doing it again. And it's not cheap! As a result, what we are ultimately trying to do with the cleaning process is to find out what will optimize the attractiveness of the fluorite and convince potential customers to take it home with them.

Now, to anyone who has spent any time trying to sell mineral specimens, it quickly becomes obvious that what the average customer wants is perfection at a bargain price. The problem that someone selling specimens has with this are twofold: (1) mining is expensive, and (2) perfection is exceedingly rare in nature. As the mine operator, we have limited control over the costs, other than trying to economize as much as we can (e.g., no business class seats on those ten-hour airline flights unless we can get a mileage upgrade). The one thing we can influence, however, is the final presentation of the “product” to the public, and this is where cleaning and preparation matter. As mentioned, perfection in nature is a rare thing. In a good year, we may end up with three to four flats of specimens we consider near perfect enough to classify them as “retail” rather than “wholesale.” In a not-so-good year, we may end up with one or two specimens. I haven't done an actual calculation, but I'm sure that the number of truly great specimens we get is a small fraction of one percent of the total. This means we must spend most of our time convincing people to take the less-than-perfect stuff if we want to have a chance of raising enough money to go back and dig for more.

When we first started this mining project in 1999, a number of collectors told us that they wanted their specimens “au natural”—just as they came out of the ground. But guess what? It turned out that no one would actually buy them in that condition. I think a lot of collectors who have never dug specimens themselves think that they come out of the ground looking like they do when they get to the cover of the collector journals, such as Rocks & Minerals. Unfortunately, at least in our case, they usually look like a 5–10-kilogram iron-stained rock with a patch of fluorite on one end. In addition, a varying amount of the fluorite has already been damaged or broken by the various forces of nature to which it has been subjected since its formation (estimated at around 260 million years ago).

Figure 1. A fluorite specimen from the 2009 collecting season before cleaning, trimming, and stabilization of the matrix.

Figure 1. A fluorite specimen from the 2009 collecting season before cleaning, trimming, and stabilization of the matrix.

Caption: Figure 2. The same specimen after preparation. Calcite overgrowth was removed with phosphoric acid, iron staining was removed with a sodium dithionite solution, insoluble overgrowth (likely quartz) was removed with an air abrasive unit using plastic particulate, damaged crystals were trimmed away from the lower portion of the specimen, and crumbling or fractured portions of the matrix were reinforced with cyanoacrylate (“super”) glue.

Caption: Figure 2. The same specimen after preparation. Calcite overgrowth was removed with phosphoric acid, iron staining was removed with a sodium dithionite solution, insoluble overgrowth (likely quartz) was removed with an air abrasive unit using plastic particulate, damaged crystals were trimmed away from the lower portion of the specimen, and crumbling or fractured portions of the matrix were reinforced with cyanoacrylate (“super”) glue.

People who collect minerals claim to want natural items, but they also desire aesthetic perfection. This concept of aesthetic perfection is a totally human preoccupation and really has nothing to do with the “naturalness” of the specimen. In fact, the two concepts are often in conflict. Nature is functional, and minerals crystallize in chemical and physical environments that are trying to reach an equilibrium state. If there happens to be a void space remaining in the host rock for attractive, free-standing crystals to form, it is just a coincidence. What we collectors think of as perfect specimens are really just accidents of nature. In trying to take less-than-perfect specimens and make them desirable to collectors, we walk a fine line between satisfying these two conflicting desires. Most specimens, if served up as they come out of the ground, will not find any buyers because they lack aesthetic appeal. If we overengineer the specimens during cleaning and preparation, collectors will no longer think of them as natural and won't buy them. Complicating the issue is the fact that the acceptable amount of treatment a specimen may undergo varies greatly within the collector community. Some people are more concerned with aesthetics; others are more concerned with scientific integrity. In preparing and marketing mineral specimens, one must find some sort of middle ground where these two opposing criteria are least violated for the maximum number of potential customers.

In our case, we've found that, as a rule, people will not purchase a 10- kilogram rock with a patch of fluorite on one end, so these specimens need to be trimmed. In addition, most specimens also have spots of unacceptable damage that must also be trimmed. Using hydraulic rock splitters to do the trimming sometimes works, but this technique often results in popping the large, gemmy, twinned crystals that everyone likes right off the matrix as it breaks. Sometimes the entire specimen just explodes into random bits. For this reason, we often need to use a saw to trim specimens. Many collectors do not like saw cuts on the matrix of their specimens because it seems a violation of its naturalness, so we then need to disguise the saw cuts (at least on the specimens we want to get a good price for) by roughing them with a hand-held pneumatic chisel. This imparts vibration to the specimen that can cause the large twinned crystals to jump ship again. If we think a crystal may come loose in the process, it must be reinforced with some super-glue at its base. This, again, tends to be seen as a violation of the specimen's naturalness by some collectors. At this point, we reach the conclusion that there is a good bit of truth to the saying that you can please all of the people some of the time, and some of the people all of the time, but you can never please all the people all the time.

So, I guess the moral of the story is that if you really want your fluorite specimens as close to natural as they can be, please get in touch, and we'll be happy to set some aside for you. Just don't expect a large, undamaged, gemmy, dark green crystal perched aesthetically in the center of a bit of matrix that is just the right size to complement it. If we ever find one like that, we'll be keeping it for ourselves!

Jesse Fisher is a life-long mineral collector, holds an MS degree in geology, and is currently a partner in the specimen recovery project at the Rogerley mine, Weardale, Northern England.

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