Joegoldsteinite
Chemical formula: Mn<sup>2+</sup>Cr<sup>3+</sup><sub>2</sub>S<sup>2-</sup><sub>4</sub>
Joegoldsteinite is an extremely rare manganese and chromium sulfide, identified exclusively in enstatite meteorites.
Properties
- Luster
- Metallic
- Transparency
- Opaque
- Crystal system
- Cubic
Diagnostic features
## Identification Identification of joegoldsteinite is possible only through advanced laboratory techniques. It requires chemical composition analysis using an electron microprobe (EDS/WDS) and crystal structure studies by electron backscatter diffraction (EBSD). In a scanning electron microscope image (BSE), it appears as phases of intermediate brightness, embedded in daubréelite. ## Distinguishing from Similar Minerals It can be confused with other sulfides from the linnaeite group, such as daubréelite (FeCr₂S₄) or indite (FeIn₂S₄), with which it forms solid solutions. Differentiation is based solely on precise measurement of the proportions of manganese, iron, and chromium in chemical analysis. ## Crystal Forms It is observed exclusively in the form of anhedral (irregular) grains, occurring as inclusions within larger crystals of other sulfides.
Geological environment
## Genesis Joegoldsteinite forms under extremely reducing conditions, with very low oxygen and sulfur fugacity. Such an environment prevailed within the parent bodies of EL-type enstatite chondrites, from which meteorites containing this mineral originate. It crystallized from the primordial matter of the Solar System during metamorphic processes occurring on asteroids. ## Mineral Associations This mineral occurs in close association with other sulfides typical of enstatite meteorites. It is most often found as an inclusion in daubréelite, and also in association with troilite, niningerite, alabandite, and metals: kamacite and taenite. ## Localities The only confirmed locality for joegoldsteinite is the Indarch meteorite, an EL6-type enstatite chondrite, which fell in 1891 in what is now Azerbaijan. This is the type locality for this mineral.
Rarity
Extremely rare
For collectors
## Quality Criteria Joegoldsteinite is not available on the collector's market and is not traded. Its value is purely scientific. Specimens of the Indarch meteorite, in which it was identified, are held in institutional and museum collections, such as the Center for Meteorite Studies at Arizona State University. For a scientific institution, any fragment, even the smallest, containing this mineral is valuable, allowing for further research.
Care and storage
## Cleaning Due to its microscopic size and occurrence as inclusions within a delicate meteorite matrix, specimens containing joegoldsteinite are not subject to cleaning in the traditional sense. Any interventions are carried out exclusively under laboratory conditions. ## What to Avoid All chemicals, moisture, ultrasound, and sudden temperature changes should be avoided. The matrix of enstatite meteorites is very sensitive to terrestrial conditions, especially to oxidation in contact with moisture and atmospheric oxygen. ## Storage Specimens containing joegoldsteinite, being fragments of scientifically valuable meteorites, require storage under specialized conditions. Desiccators filled with nitrogen or another inert gas are most commonly used to prevent mineral degradation.