If you are new to collecting, it's easy to be overwhelmed by the sheer number of mineral types that are sold in the collectors market, and you might find it difficult to understand whether a mineral you have been offered is a "good deal". Since every mineral is unique, it's very difficult to answer this question! In fact, there have been many attempts in the industry to set standards for pricing that have been met with a spectrum of reactions from praise to skepticism to outright scorn!
In this section, we will try to give you a sense of what price would generally be considered reasonable pricing for minerals, based on a variety of criteria. Unlike say, a comic book, there is no real "standard" or "accepted fair price" for a mineral. And as they say, one persons trash is another's treasure. So all of the advice here should be taken only as a general guide, and not as the gospel truth on the matter. We offer this guide based on years of collecting, attending auctions & shows, and scouring the web for deals on minerals.
As noted above, pricing a mineral can be tricky business- but you can usually look at several criteria to determine whether a mineral should be priced at a low, average, high, or premium price range.
These factors include the following considerations:
- Species - What type of mineral or rock is this? Is it a rare species, or a relatively common one?
- Grade - Most minerals have a fairly clear "grade". This grade is applied with a significant curve based on the relative accessibility of that type of specimen- where junk or industrial grade versions, usually make up 70% of all specimens, rising to lapidary grade, which might make up another 10%, to mid-grade grade, which make up another 10%, to collector grade, which represent fewer than 6% of all specimens, and finally to investor grade which make up another 3%, and lastly, gem grade would usually be only 1% or fewer of all specimens on the market. Not all low-grade minerals are ugly and unattractive - the grade is more reflective of the overall quality and rarity of that specimen vs common examples. A very nice looking quartz might only rate as average, while a gem grade quartz must be truly exceptional.
- Locality - Is this specimen from a hard-to-access location, a closed mine or adit, or a place where the mineral is found in very limited quantities?
- Appearance - Is the mineral especially visually attractive? For example, does it have very shiny luster, richly saturated color, or very perfect and symmetrical crystal form?
- Size - Anyone who has ever bought a diamond knows that "size matters" and its perhaps the biggest consideration for gem-grade mineral and crystal specimens. For very high value gems like diamonds, they tend to be measured in carats (5 carats = 1 gram). Lower grade specimens are usually measured in terms of either grams or centimeters. Most serious dealers use the metric system (MM/CM) and (G/KG), to denote sizing and weight since these are the units that are used most often throughout the world; and inches and feet are generally considered peculiar to collectors, miners, and dealers outside the US market.
- Damage - For minerals and crystals this is easier to assess than for rocks. Crystals generally have what would be considered a "euhedral" form or an "ideal" form, shape, and color. If the mineral you have, has this form, its more valuable. But digging for crystals is difficult - and especially for softer or more brittle minerals - it's easy to damage a mineral in extraction. Damage to the tip or edge of a crystal can greatly reduce its value vs. a mineral which is damage free. Damage to edges is sometimes called "chatter" and may be overlooked if a specimen is very nice in other regards.
- Association/Inclusion/Coating - Many rocks fetch higher prices based on specific associations of two or more minerals, like dark Grey-Black Smoky Quartz and Aqua Blue Amazonite, or Purple Fluorite and Pink Rhodochrosite. These "combo" minerals may be worth more than the sum of their parts. In other cases, an "inclusion" of a mineral inside another crystal can be either an attractive addition or a detractor. For example, there are some Amethyst (quartz) crystals that have inclusions of bright red hematite that are very attractive. Other quartz may have coatings that can be removed, but may be left in place to add to the visual appeal. This is one of the most "subjective" markers of value.
- Twinning - Some crystals grow in the form of "twins" where two crystals have grown together at the same or different rates, at a very specific angle. There are terms like "Spinel Law" or "Japan Law" to explain the exact nature of this twinning formation. Finding certain species that do not commonly grow in twins, can cause the price to greatly increase for that mineral. This is one of the ways that being an expert can give you an advantage in buying minerals - as you may be able to spot a rare twinning that someone else may not recognize is present in their sample.
- Provenance - Mineral collecting is one of the worlds oldest hobbies, and as such, there have been many very famous collectors and collections, and minerals often have changed hands many times. Having a mineral that was formerly owned by a famous museum or collector, can add to the appeal of that minerals "provenance". This is also enhanced if you have an old "collector card" that was provided with the mineral. Any serious collector should ask for an official collector card with every fine mineral specimen they purchase, to establish a "chain of custody" for that mineral. Older specimens often include hand-written cards, sometimes with wonderful calligraphy, which can add to the appeal of that specimen to a serious collector.
- Alteration - Alteration can be either natural or man-made. Alteration tends to reduce the value of a mineral specimen. Examples of man-made alteration include cutting, polishing, or adding "coatings" to a mineral. Some types of alteration are considered more acceptable than others, depending on the species.
- Cleaning: Cleaning is usually accepted as part of the preparation process of selling a rock. Some species, like Pyrite are almost always treated with cleaning agents to bring out their beauty and luster - and it's expected and does not affect value in this case. This is also considered somewhat acceptable for these minerals. In some cases, cleaning can be destructive, like if it removes iridescence, removes natural striations, or causes scratches on the specimen.
- Cutting: Cutting of some rocks like labradorite is considered fairly common, and an acceptable way to show off the beauty of that rock - although some purists eschew this practice. In other cases, cutting is considered deceptive - like if a mass of emerald is cut into a six sided column to make it appear like it was a euhedral growth. Savvy buyers can spot this and will avoid such specimens.
- Dissolution of Coatings: Some minerals like garnets are often coasted with a thick mass of calcite, which is dissolved away using hydrochloric acid. This is considered somewhat acceptable for these minerals if performed properly and thoroughly. Other minerals like quartz usually come out of the ground VERY dirty, and must be soaked in water, acid, "iron off" and other chemicals. This process, if not performed carefully, can cause discoloration of the groundmass and may detract from the value.
- Polishing/Tumbling: Rough or Lapidary grade minerals are those which generally lack euhedral growth patterns, and are often chunky, opaque versions of their more expensive counterparts in the same species. A rough mineral with a dull or waxy luster may be processed in a rock tumbler, or by grinding the rock on a grinding wheel, sandblasting it, and other abrasive actions. Depending on what the mineral started out like, the polishing process can either increase or decrease the value. If the piece started out as a dull piece of lapidary grade stone, and came out shiny and beautiful, it would be expected to increase the value. On the other hand, if you started with a mid grade euhedral crystal, then polished the faces of it, that might be considered destructive and reduce its' value.
- Oxidation/Fading: Some minerals like pyrite may oxidize and get coated with an unattractive rust or powder on the outside. Others like Fluorite or Vivianite may be very sensitive to UV or light in general, and become cloudy, losing their color or clarity. In some cases the mineral can be restored to its original beauty, but not always. Careful handling of minerals can help ensure they are retained in the correct conditions to retain their more valuable characteristics.
- Heat Treatment & Irradiation: Once again, some treatments are considered "common" and do not greatly reduce the value of a mineral. This may include things like heat treating a Tanzanite to increase its color. This is such a common practice, that most dealers simply assume these are heated unless otherwise noted. But heating of some minerals or use of techniques like irradiation can be destructive. This is sometimes just because a collector values "purity" but other times, its because the treatment actually alters the mineral, or may be temporary, leaving the buyer excited at first, and then disappointed later.
- Mounting: Usually it's best to leave a mineral in its natural state - but sometimes a mount may be constructed to ensure the mineral stands upright, or that a certain face is shown. Mounting can add to the value of a specimen, but it should always be done in a way that is non-destructive and not permanent. Permanently gluing a mineral to a mount can damage its value and cause damage to the specimen when the buyer wants to remove it. It used to be common practice to glue minerals to a piece of styrofoam and place that in a small paper box. This is no longer considered very proper handling of most samples, but there is a niche of collectors who seek out these samples due to their rather obvious provenance as old pieces.
- Uniqueness - This is a sort of catch-all on the part of the seller- is the specimen unique in a noticeable way? This might be an uncommon or beautifully colored inclusion, phantom, or faden, an optical property like iridescence or chatoyancy, an odd shape like a geometric shape, an anthropomorphic feature like a hand or an eye, a weird resemblance like an animal or insect, or a distinctive crystal growth pattern like a gwindel or an attractive symmetry, etc.
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Name of Species:
Enter the name of the primary mineral species:
Locality of Species:
Enter the locality of the primary mineral species:
Estimated Average Price for a Miniature sample of the Species:
Enter an assumption for a very average piece of this material:
Species Quality / Rarity:
Rate the overall rarity of your specimen, with 1 being the most common and 10 being an extremely rare and duiifficul to obtain version of this mineral:
Locality:
Rate the locality, with 1 being easy to access and still producing abundent samples, and 5 being a closed mine or location that is impossible to access:
Appearrance/Clarity:
Rate the appearance or clarity of this specimen, with 1 being very plain, dull and unremarkable and 5 being the best possible representation of this species:
Size:
Estimate the size of your specimen, with 1 being very small, and 5 being an exceptionally large specimen:
Damage:
Rate the damage of your specimen, with 1 being highly damaged and 5 being in perfect condition:
Association:
Rate the size of your specimen, with 1 being an undesirable associated mineral and 5 being a highly desirable association:
Twinning:
Rate the twinning of your specimen, with 0 being no twinning and 2 being perfect twin growth:
Provenance:
Rate the provenance of your specimen, with 0 indicating you have no idea where the mineral comes from, and 2 meaning that is has desirable provenance:
Unique Attribute:
Does you specimen have another identifiable unique attribute - like a cool pseudomorph, a desirable shape, unusual color, other interesting attribute that makes it unique and special.
Detractors:
Enter any alterations that have occurred on this specimen that might detract from its value:
Improvements:
Enter any alterations that have occurred on this specimen that might increase from its value:
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