 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. There is a popular notion about the "mineral pricing triangle": Big, gem, cheap - you can have two of these three. You can get a big gem, but not cheap... You can get a cheap gem, but not big... And you can get a big, cheap piece, but it will not be a gem!
Dynamic Earth Collection: Mineral Identification and Pricing Tools
Specimen Pricing List
Mineral Appraisal Calculator
Identify a Mineral Specimen
Understanding Mineral Pricing Considerations
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? Rarity is sometimes a controversial subject, because some dealers will assign the term rare very loosely. Generally rarity can be assessed in a couple ways. First - are there only a few known occurrences? If there are only two or three places in the world the mineral is found, it may be considered rare. But this also requires that the mineral is not particularly abundant at those few localities. Another measure of rarity is the idea of a "one time find", for example, a blue cap '98 Sapo tourmaline or a Polish Prodigy fluorite is considered rare. Tourmaline and Fluorite are not very rare, but pieces from these specific finds, are very limited. So rarity of a species is one thing, but rarity of a specific attribute can also play into the notion of rarity. In addition, the price impact of rarity is entirely driven by market demand. There are many rare minerals that simply have no significant demand - so even though they are rare, they are not valuable, because few people are looking to add that species to their collection.
Common Species #343: Qtz. Cluster Bahia, Brazil Uncommon Species #721: Carletonite Poudrette Qry, MSH, QC, Canada Rare Species #493: Phosphophyllite Bolivia
- Grade - Most minerals can be assigned a fairly clear "grade" which would be agreed upon and accepted by other mineral collectors. 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.
Mid Grade #366: Quartz Mt. Ida, Arkansas, USA Collector Grade #343: Qtz. Cluster Bahia, Brazil Investor Grade #717: Qtz. v. Herk. Diamond Ace of Diamonds Mine, NY, USA
- Locality - When considering the price impact of locality, first and foremost, you must have a definitive record of where the specimen originated. This is part of why provenance is so important. Some minerals' origin location is readily identifiable, because that mineral may only come from one location, or may have a very distinct appearrance when it originates from a specific known location. For example, many collectors could readily identify a specimen from Erongo, Namibia, based on the combination of minerals and their appearrance. A Chibuku amethyst can often be identified because of its distinctive color and saturation. But no assumed locality identification is as good as a definitive record of the origin of that piece. So it is always best when collecting to retain records of the specimen type, locality (as specific as possible) and the date of collection, if known. Once you have determined the locality, then you must ask questions about the locality like: Is this specimen from a hard-to-access location? A closed mine or adit? A place where the mineral was found in very limited quantities or only for a short time? Is the locality the same as the holotype, (also known as the type locality) for this species? These factors can increase the minerals' probable value to other collectors, based on locality.
Common Locality #343: Qtz. Cluster Bahia, Brazil Uncommon Locality #755: Fluorite Choir Area, Mongolia Rare Locality #773: Molybdenite Antarctica Type Locality #473: Vauxite Siglo Veinte Mine, Brazil
- Appearance - Appearance may be the single most important factor in determining price. Very aesthetic minerals have appeal beyond just geology enthusiasts, and are enjoyed by individuals with little knowlege of mineralogy. A very beautiful amethyst cathedral may make a nice piece of home decor, so even though they are not super rare, they can fetch a high price. Similarly, a multi-colored "rainbow" Bergmännisch Glück fluorite will be more desired than a brightly colored fluorite with only one dominant hue. A very shiny pyrite will be more valuable than a pyrite which is not as lustrous. Beauty is in the eye of the beholder - and appearrance is a subjective measure - but most collectors can agree on certain standards including high clarity in crystals, perfect, sharp terminations, and shiny surface luster in metallic sulfides. Isolation of crytals against the matrix can also be seen as a desirable factor to make the crystals really pop against a more drab background. Additionally, concepts like symmetry, balance and how the mineral "self stands" are factors that are somewhat intangible, but can make a mineral display in a way that appears more aesthetic.
Rough Appearance #233: Sulphur (Native) El Desierto Mine, Bolivia Decent Appearance #1518: El Desierto Mine, Bolivia Exemplary Appearance #859: Sulphur (Native) El Desierto Mine, Bolivia
- 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. Size of minerals is typically denoted by a series of names which describe the general size range from micromounts to museum sized pieces, as explained on the about the collection page.
Thumbnail #344: Qtz. v. Amethyst Brandberg, Erongo, Namibia Miniature #1419: Qtz. v. Amethyst Veracruz, Mexico Small Cabinet #840: Qtz. v. Amethyst La Manche, NL, Canada Large Cabinet #422: Qtz. v. Amethyst Anahi Mine, Bolivia
- 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.
Damage free #413: Qtz. on Albite Poison Ivy Pocket, OK, USA Some broken tips #952: Qtz. / Iron Rose Jinlong hill, China
- 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, fluid or gas inside another crystal can be either an attractive addition or sometimes, 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.
Common Combo #555: Chrysocolla / Malachite Katanga, Congo [DRC] Nice Combo #864: Amazonite w/ Smoky Qtz. Park County, CO, USA Desirable Combo #452: Garnet v. Spessartine Tongbei, Fujian, China Exemplary Combo #1495: Fluor / Pyr. / Gal. Milpo mine, Atacocha, Peru
- 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.
Japan Law Twin #1150: Amethyst (Japan Law) Madagascar Drill-bit Penetration Twin #986: Cinnabar Nikitovka Deposit, Ukraine Sixling Twin #805: Rutile / Hematite Novo Horizon, Brazil
- 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 may be in a different language, which can add to the appeal of that specimen to a serious collector. Rare pieces may also provide very detailed notes on the exact collection location, date, origin, and significance of that specimen.
Hand-Written #776: Ferrimolybdite Antarctica Collection Details #792: Qtz. v. Flint Flint Ridge, OH, USA Famous Collector #648: Tremolite La Higuera, Chile
- Alteration - Alteration can be either natural or man-made. Alteration may increase or 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.
Polished #965: Polychrome Jasper Madagascar Cut #802: Black Skin Agate India Heated #301: Qtz. v. Citrine Brazil Mounted #1168: Pyromorphite Moulai-Azza, Morocco
- Uniqueness - This is a sort of catch-all modifier that may be applied by a 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; a unique property like magnetism; or a distinctive crystal growth pattern like a gwindel or an attractive symmetry, etc.
Donut Shape #423: Ludlamite Mina Nueva, Bolivia Rock-n-Roll Hand #830: Stibnite Hunan, China Magnetic #372: Magnetite v. Lodestone Clear Creek Canyon, CO, USA
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