Monimolite
Chemical formula: Pb<sup>2+</sup><sub>2</sub>Sb<sup>5+</sup><sub>2</sub>O<sub>7</sub>
Monimolite is a rare lead and antimony oxide mineral, occurring as small, resinous-lustered grains and masses.
Properties
- Mohs hardness
- 5-6
- Luster
- Resinous to sub-metallic
- Streak
- Yellowish to greyish
- Density
- 6.58
- Cleavage
- None
- Fracture
- Uneven to sub-conchoidal
- Transparency
- Opaque
- Crystal system
- Cubic
Diagnostic features
## Identification Helpful features for identifying monimolite include its high density, resinous luster, characteristic greenish-yellow to brown colors, and occurrence as small, embedded grains. Its reaction to hydrochloric acid (it dissolves) is also a diagnostic feature, but requires sample destruction. ## Distinguishing from Similar Minerals Monimolite can be confused with other rare oxides from the pyrochlore group or similar secondary lead and antimony minerals. Accurate differentiation is often impossible without advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS). ## Crystal Forms Monimolite crystals are extremely rare and usually poorly developed, taking the form of small, regular (octahedral) crystals. It is most commonly found as irregular grains and massive aggregates.
Geological environment
## Genesis Monimolite is a secondary mineral, forming in the oxidation zones of ore deposits, especially in metamorphic rocks such as skarns, rich in manganese, lead, and antimony. It forms as a result of the alteration of primary minerals containing these elements. ## Mineral Associations This mineral often co-occurs with other minerals typical of this environment, such as magnetite, hausmannite, barite, calcite, tephroite, richterite, as well as other rare lead and antimony minerals, e.g., from the pyrochlore group. ## Localities The most important and classic monimolite localities are in Sweden, in the Harstigen and Långban mines in the Värmland region. Outside of Sweden, its occurrence has been reported in small quantities in Franklin, New Jersey (USA) and in the Kombat mine in Namibia.
Rarity
Very rare
For collectors
## Quality Criteria For collectors, the most important criterion is the presence of well-formed, even if small, monimolite crystals, which is extremely rare. Rich aggregates of grains that clearly contrast in color with the host rock are also valued. Specimens from type localities (Harstigen, Långban) have particular historical and scientific value. ## Popular Localities The most sought-after specimens by collectors come from the historic localities in Sweden – Harstigen and Långban. Material from these localities is considered classic and serves as a reference point for this mineral.
Care and storage
## Cleaning Due to its rarity and potential fragility, only gentle cleaning with a soft, dry brush is recommended to remove dust. Avoid water and any cleaning solutions. ## What to Avoid Monimolite contains lead, which is a toxic element. Avoid inhaling dust that might be generated during processing or damage to the specimen. It is necessary to wash hands after any contact with the mineral. Avoid contact with acids, which can damage it. Store away from moisture. ## Storage Monimolite specimens should be stored in a dry place, preferably in a closed collector's box, to limit exposure to dust and moisture and prevent accidental contact. Due to its toxicity, keep it away from children and pets.