Mampsisite
Chemical formula: Ca<sub>4</sub>Al<sub>2</sub>(OH)<sub>12</sub>(CO<sub>3</sub>)· 5H<sub>2</sub>O
Mampsisite is a newly discovered, colorless mineral from the hydroxycarbonate group, forming microscopic, platy crystals.
Properties
- Luster
- Vitreous
- Streak
- White
- Density
- 2.11
- Cleavage
- Perfect on {0001}
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Identification of mampsisite is impossible without advanced analytical techniques. It requires the use of a scanning electron microscope (SEM) for observing crystal morphology and energy-dispersive X-ray spectroscopy (EDS) or similar methods to confirm chemical composition. Reaction with hydrochloric acid (effervescence) indicates the presence of carbonate, but this is a common feature for many minerals. ## Distinguishing from Similar Minerals Based on macroscopic appearance (white, earthy coatings), mampsisite is indistinguishable from calcite, aragonite, vaterite, or other carbonates and secondary minerals. Its unique crystal structure and chemical composition, confirmed by X-ray diffraction (XRD), are crucial for definitive identification. ## Crystal Forms Mampsisite forms very small, hexagonal, platy crystals. They usually occur in the form of rosette-like or spherulitic (spherical) aggregates, forming porous, chalk-like masses.
Geological environment
## Genesis Mampsisite is a secondary mineral, formed in an anthropogenic environment. Its formation is associated with the weathering and transformation processes of ancient lime-based mortars and plasters. It forms as a result of reactions between calcium carbonate (calcite) and aluminosilicates (e.g., clay minerals) present in the mortar, under conditions of high pH and water availability. ## Mineral Associations At the type locality, mampsisite co-occurs with calcite, vaterite, aragonite, gypsum, and minerals from the tobermorite group. ## Localities The only confirmed occurrence of mampsisite in the world is its type locality – Mamshit National Park in the Negev Desert, Israel, where it was found in historical building mortars.
Rarity
Extremely rare
For collectors
## Quality Criteria As a micromineral, the collector's value of mampsisite is determined by the quality and richness of the aggregates on the rock matrix. Most desirable are specimens with well-formed, distinct rosettes or spherulites that can be observed under a microscope. The aesthetics of the entire specimen, including contrast with the substrate, is also important. Since it is a monotypic mineral (known only from one location), every specimen is valuable for specialized collectors. ## Popular Localities The only source of specimens is the type locality in Israel. The acquisition of material from this site is strictly regulated, as it is a national park and an archaeological site.
Care and storage
## Cleaning Specimens should be handled with utmost care. Due to the microscopic size of the crystals and their fragility, mechanical or chemical cleaning is not recommended. It is safest to leave the specimen undisturbed. ## What to Avoid Avoid contact with acids, which will rapidly dissolve the mineral with the release of carbon dioxide. As a hydrated mineral, it is sensitive to high temperatures, which can lead to its dehydration and destruction of its structure. It should be protected from moisture and water, which can affect the stability of the aggregates. ## Storage Mampsisite micromineral specimens should be stored in stable conditions, in closed, padded "micromount" boxes, to protect them from mechanical damage, dust, and humidity changes.