Thumbnail Specimens - Glacial Concretions

Glacial ConcretionMost rock and mineral collectors don’t think about how or where they will display their prized specimen pieces. Everyone loves an amazing display specimen. However…just where do you plan on displaying your specimens and how much room do you actually have for your displays? These should be questions most rockhounds and collectors ask. Your specimen size is very important. Large crystals and large mineral specimens can be wonderful and impressive. Everyone who has ever been stopped in their tracks by an exquisite large specimen on display in a rock and mineral show or museum wants some “killer” large specimens. But how does that relate to your mineral collection? If you are starting or building a mineral collection, you need to consider the sizes of your specimens.

Larger mineral specimens are generally lower quality than smaller comparable ones. This is basically due to the fact that larger specimens have more formation issues such as cloudiness, fractures, less defined precise edges, etc. They are more difficult to extract from their matrix and to get to the end collector without being damaged during mining or shipping. This also accounts for the significantly higher price for those rarer large specimens that are more perfect.

If a mineral specimen is something you just have to have, it surely is something special enough to display. It takes no time to run out of display spaces for your specimens and that happens a lot faster with larger specimens. If you live in a small house, your collection that began as something exciting can quickly become overwhelming. Many collectors have beautiful collections, but they wind up keeping their collections boxed up and stored away because they have no place to show it off. After all the arduous hours collecting and the hard earned money we have spent on our specimens, they wind up somewhere we can’t enjoy them and neither can anyone else.

Many collectors have a plan for the future, when they will turn a room, the basement or garage into a mineral display room; or build an addition on the house; or move to a larger house that will have space for the collection. Guess what …your mineral collection is now running your life choices! No one who begins collecting rocks and minerals ever thinks that someday their hobby will dictate to them to build more space or move to a larger house. Think about how you plan to enjoy and share your rocks and minerals. Will you be viewing your collection in a display cabinet from a distance or will you view it in a cabinet or on shelving close-up? Some collectors keep their specimens in drawer cabinets where the specimens are only visible when the drawer is opened. You can get glass top display cases in a variety of sizes to show off your collection.

We believe the ideal collection will include a variety of rock and mineral specimen sizes. If the collector is aware of sizes and display space available, you can build an exceptional collection. You could plan on using some shelving and a small display cabinet for most of the collection and also have a few larger exceptional specimens on your current cabinets or tables.

Although there are a few terms commonly used for mineral sizes, the exact dimension of these sizes differs, depending on the source. The “AFMS” (American Federation of Mineralogical Societies) rules, which are used in U.S. mineral show competitions, have a specified set of dimensions. Mineral dealers and collectors commonly use slight variations. The variations that exist occur mainly due to availability of display boxes or plastic cubes to display specimens in. We are not suggesting that you must use any specific dimensions for the terms; we just want you to be aware of the terminology and approximate common dimension for each size.

Guide to Mineral Sizes

(MM) - Micro mineral - a small (typically less than 1") piece of matrix with micro crystals unmounted. The term "micro mineral" depends more on the size of the crystals or specific mineral than it does on the size of the matrix. Requires magnification to identify or evaluate.

(MT) Micro mount - a mounted micro specimen, usually in a standard "micro mount" size box (Dimensions: 1.0" x 1.0" x 0.75" (2.54 cm x 2.54 cm x 1.90 cm). The matrix, where present, is typically 3/8 inch or less in maximum dimension. Some micro mounts may consist of a single crystal mounted with no matrix.

(TN) Thumbnail - fits in a standard “Perky" box dimensions 1.25" x 1.25" x 1.25" (3 cm cube).

(MN) Miniature – specimen size ranging from about 1.5 inches to about 2.5 inches across maximum dimension. Fits in a 2” (5 cm) cube

(SC) Small cabinet - 2.5 to 4 inches (6 to 10 cm) across maximum dimensions.

(LC) Large Cabinet – 4 to 6 inches (10 to 15 cm) across maximum dimension.

(MUSEUM) Museum (or Extra-Large Cabinet)- more than 6 inches (15 cm) across maximum dimension. These extra-large specimens are commonly referred to as museum…not to designate quality, but only to designate size. XL or XLS cannot be used as XL / XLS are the mining abbreviations for crystal / crystals

These size classifications are not universal. Different mineral dealers may have slightly different dimension standards for what they consider to be miniature, small cabinet, large cabinet and museum or extra-large cabinet. The dimensions for Thumbnail and Micro mount sized minerals are fairly standard because the standard display boxes limit their size.

Many of our customers have requested thumbnail specimens from us, so we are now creating this Thumbnail Specimens page where we will list thumbnail specimens. They will be in random order and like items grouped together whenever possible. You talk, we listen! Happy Thumbnail hunting!

Specimens are set on Mineral Tack unless stated otherwise