Witherite: England (1.89). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Witherite
Easy to cut but too soft and fragile for jewelry, a faceted witherite would make an unusual addition to a gem collection.
Witherite Information
| Data | Value |
|---|---|
| Name | Witherite |
| Colors | Colorless, white, gray with a tinge of yellow, green, or brown. |
| Crystallography | Orthorhombic. Crystals twinned to yield pseudohexagonal dipyramids; prismatic; globular, botryoidal; granular; fibrous. |
| Refractive Index | 1.529-1.677 |
| Luster | Vitreous to resinous. |
| Fracture Luster | Resinous |
| Hardness | 3-3.5 |
| Wearability | Poor |
| Fracture | Uneven |
| Specific Gravity | 4.27-4.79 |
| Birefringence | 0.148 |
| Cleavage | Distinct 1 direction |
| Dispersion | Low |
| Luminescence | See "Identifying Characteristics" below. |
| Luminescence Present | Yes |
| Luminescence Type | Fluorescent, Phosphorescent, UV-Long, UV-Short, X-ray Colors |
| Transparency | Transparent to opaque. |
| Absorption Spectrum | Not diagnostic. |
| Formula |
BaCO3 |
| Pleochroism |
None. |
| Optics |
a = 1.529; β = 1.676; γ = 1.677. Biaxial (-), 2V = 16°. |
| Optic Sign | Biaxial - |
| Etymology |
After William Withering, an English physician and mineralogist who first described the mineral. |
| Occurrence |
A low-temperature mineral in hydrothermal vein deposits. |
Large witherites with unusual ball-like shapes composed of radial needle formations. 13.0 x 9.0 x 6.0 cm, Bethel Level, Cave-in-Rock District, Illinois, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.
Comments
Witherite forms a series, as the barium (Ba) analogue, with strontianite, the strontium (Sr) analogue. Both belong to the aragonite mineral group.
Although an uncommon mineral, witherite has had numerous commercial uses. However, as cut gems, witherites have little to recommend them by way of beauty or wearability. Nevertheless, faceting adds rarity and thus interest for those pursuing a gem collection of unusual specimens.
Manufacturers have used the mineral witherite in the production of glass, cement, paint, and other materials. In the late 18th century, Josiah Wedgwood also used witherite to produce the pottery known as jasperware. 12K Wedgwood earrings, gold border with classic sage green jasperware with white relief. Photo by Housing Works Thrift Shops. Licensed under CC By-SA 2.0.
Identifying Characteristics
Witherites effervesce in acid. Please note that acid testing is a destructive test. Use this procedure only as a last resort for identification and never on a finished gem. (Also, note the information on this material’s toxicity in the “Care” section below).
Witherites can fluoresce or phosphoresce bluish white. They can also show the following:
- Green and yellow in shortwave (SW) ultraviolet light (England) with phosphorescence.
- Yellowish, with phosphorescence, in longwave (LW) UV light.
- Fluoresces in X-rays.
A large, sharp, lustrous, pseudo-hexagonal yellowish witherite crystal attached to a thin vein of yellow fluorite. The witherite shows bluish white fluorescence; the fluorite blue. These crystals, approximately 4.8 x 4.4 x 3.2 cm, come from the Minerva No. 1 Mine, Cave-in-Rock, Cave-in-Rock Sub-District, Illinois – Kentucky Fluorspar District, Hardin Co., Illinois, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.
Synthetics
Scientists have synthesized witherite-strontianite series crystals for mineralogical research. However, there is no known jewelry use for this material.
Enhancements
No known enhancements.
Sources
The Minerva Mine in Rosiclare, Illinois produces large yellowish crystals.
In the United Kingdom, various sites — including the type locality (Brownley Hill Mine, Alston Moor, England) — produce fine crystals.
Other notable sources of crystals include the following:
- United States: Arizona; California; Kentucky; Montana; Lockport, New York.
- Austria; Germany; Czech Republic; France; Japan; Russia; Slovakia.
Unusually lustrous columnar witherites, 7.6 x 7.5 x 5.1 cm, Nentsberry Haggs Mine, Alston Moor District, Cumbria, England. © Rob Lavinsky, www.iRocks.com. Used with permission.
Stone Sizes
Lapidaries normally don’t cut witherites into cabochons, since their colors are too pale to be attractive in such a form. Faceted gems, even those under 5 carats, are usually more translucent than transparent.
Care
You’ll more likely find witherites, if at all, in mineral collections than jewelry collections. With a hardness of only 3 to 3.5 and distinct cleavage, these would make poor jewelry stones. Although easy to cut, witherites prove difficult to polish. If worn, reserve them for occasional use and make sure they don’t rest for long periods against your skin. Over time, they will react to sweat. Use protective gem settings only.
Lapidaries who cut witherite should take precautions against inhaling dust from this material. Witherite (barium carbonate) is toxic if ingested. Finished gems and crystals, however, should pose no risk. (Oddly enough, witherite was once used in sugar refining).
For cleaning recommendations, consult our gemstone jewelry care guide.
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