Priceite

Chemical formula: Ca₂B₅O₇(OH)₅·H₂O

Priceite is a historical name for a massive, earthy, or chalk-white variety of colemanite, a borate mineral.

## Characteristics Priceite is a name used for a massive, compact, and most often white variety of colemanite. It occurs as earthy, chalk-like, or porcelain-like aggregates that rarely show visible crystalline structure. Unlike typical colemanite, which forms well-developed, vitreous crystals, priceite has a dull, earthy appearance. It is a relatively soft and light material. ## Physical Properties As a variety of colemanite, priceite shares its basic physical properties. Its Mohs hardness is about 4.5, meaning it can be scratched with a knife. The density is approximately 2.42 g/cm³. Although crystalline colemanite exhibits perfect cleavage, this feature is unobservable in compact priceite aggregates. The luster is usually dull or earthy, and the mineral is opaque. ## Colors and Varieties Priceite is typically white, grayish, or yellowish. The name itself defines a variety of colemanite. A very similar, if not identical, form is pandermite, from Turkey, which is also a massive, white variety of colemanite. Currently, both names (priceite and pandermite) are considered synonyms of colemanite in mineralogy. ## History and Name The name priceite was given in 1873 by Benjamin Silliman Jr. in honor of Thomas Price, a metallurgist from San Francisco, who first analyzed the material. The mineral originated from the vicinity of Chetco in Curry County, Oregon, USA. Later studies showed that it is identical to colemanite, which was described earlier, hence the name priceite is now mainly of historical significance. ## Uses Colemanite, of which priceite is a variety, is an important source of boron. This element is used in the production of borosilicate glass (e.g., Pyrex), ceramics, enamels, and also in agriculture as a component of fertilizers. Priceite specimens are mainly of collector's interest, especially those from the original locality in Oregon.

Properties

Mohs hardness: 4.5
Luster: Earthy, dull, rarely vitreous
Streak: White
Density: 2.42
Cleavage: Perfect on {010}, good on {001}
Fracture: Uneven to conchoidal
Transparency: Opaque, translucent on edges
Crystal system: Monoclinic

Diagnostic features

## Identification Priceite is most easily recognized by its massive, chalk-like or porcelain-like form and white color. It is relatively soft (Mohs hardness 4.5) and light. Its occurrence in borate deposits in arid climates is also an important diagnostic clue. ## Distinguishing from Similar Minerals It can be confused with chalk (much lighter and softer), magnesite (reacts with hydrochloric acid), or howlite (often co-occurs, but is slightly harder and may have gray veins). Unlike ulexite, priceite does not have a fibrous structure. ## Crystal Forms Priceite by definition is massive, compact, or earthy. The crystalline form to which it belongs (colemanite) forms short, prismatic or tabular crystals with a vitreous luster, belonging to the monoclinic system.

Geological environment

## Genesis It is a secondary mineral, formed in sedimentary borate deposits under desert or semi-desert climatic conditions. It forms in saline lake basins (so-called playas) as a result of alteration and weathering of primary borate minerals, such as ulexite and borax, under the influence of calcium-rich waters. ## Mineral Associations It most often co-occurs with other borate minerals, such as colemanite (of which it is a variety), ulexite, borax, hydroboracite, and howlite. Celestite, calcite, and gypsum may also accompany it. ## Localities The historical, type locality for priceite is the vicinity of Chetco in Curry County (Oregon, USA). Much larger and more important deposits of colemanite (including its massive varieties) are found in California (USA), especially in the Death Valley region and in the Kramer District (Boron mine). Deposits are also known from the Panderma region in Turkey (where a similar variety is called pandermite), as well as in Argentina and Kazakhstan.

Rarity

Not very common

For collectors

## Quality Criteria Since priceite is a historical name, specimens from the original locality in Oregon, with appropriate documentation confirming their origin, have the greatest collector's value. For colemanite in general, large, well-formed, transparent crystals with strong luster, often in attractive groups, are sought after. Massive forms like priceite are valued mainly by collectors specializing in rare varieties or minerals from specific localities. ## Popular Localities For crystalline colemanite, the most prized specimens come from mines in California, such as the Lila C. Mine, Ryan, or mines in the Boron area. Turkish pandermites are also classics. "Priceite" specimens from the type locality in Oregon are historically important but extremely rare on the market.

Care and storage

## Cleaning Specimens should only be dry-cleaned, using a soft brush or compressed air to remove dust. Contact with water is highly inadvisable, as it can lead to partial dissolution and damage to the mineral's surface. ## What to Avoid Water, ultrasonic cleaners, and all chemical agents, especially acids, should be strictly avoided. The mineral is sensitive to humidity changes and should not be stored in damp conditions. As a relatively soft mineral, it is susceptible to scratches. ## Storage It is recommended to store in a dry place, preferably in a closed box or display case, possibly with a desiccant (e.g., silica gel). It should be isolated from harder minerals to avoid mechanical damage.