Teschemacherite
Chemical formula: (N<sup>3-</sup>H<sub>4</sub>)HCO<sub>3</sub>
Teschemacherite is a rare, organic ammonium bicarbonate, forming colorless or yellowish, unstable crystals, most commonly found in guano.
Properties
- Mohs hardness
- 1.5
- Luster
- Vitreous
- Streak
- White
- Density
- 1.5
- Cleavage
- Perfect on {010}
- Fracture
- Conchoidal
- Transparency
- Transparent to translucent
- Crystal system
- Orthorhombic
Diagnostic features
## Identification The key diagnostic feature of teschemacherite is its very low hardness (1.5 on the Mohs scale) and a strong, characteristic ammonia odor, which intensifies upon slight heating or contact with moisture. This mineral is also water-soluble. Its occurrence in a specific environment (guano deposits) is also an important clue. ## Distinguishing from Similar Minerals Teschemacherite can be confused with other unstable organic minerals or ammonium salts, such as sal ammoniac (ammonium chloride). However, sal ammoniac crystallizes in the isometric system and does not have such an intense ammonia odor in dry conditions. Other carbonates and sulfates found in caves (e.g., gypsum) are much harder and do not emit an ammonia odor. ## Crystal Forms Teschemacherite crystals are typically prismatic, often elongated, with a cross-section resembling a square or rectangle. It also occurs in granular aggregates, stalactites, as well as loose masses or crusts on other materials.
Geological environment
## Genesis Teschemacherite is a mineral of organic origin. It forms as a result of the decomposition of nitrogen-rich organic matter, mainly bird (guano) or bat droppings, under conditions of low humidity and temperature. It is a product of the reaction of ammonia with carbon dioxide and water. ## Mineral Associations It most often co-occurs with other minerals formed in guano deposits, such as struvite, newberyite, phosphammite, as well as gypsum and calcite. ## Localities The most important localities for this rare mineral are in areas of guano accumulation. It was discovered on Saldanha Bay Island in South Africa. It is also known from the Chincha Islands (Islas Chincha) in Peru, Guido Cave in Sardinia (Italy), and several caves in South Australia.
Rarity
Very rare
For collectors
## Quality Criteria Due to its rarity and instability, well-formed, sharply terminated, and transparent crystals are most valued. Crystal size and the absence of mechanical damage are important. Specimens on rock matrix or in association with other rare guano minerals are particularly sought after by specialized collectors. Color is not a key criterion, although colorless, pure crystals are rated higher. ## Popular Localities Historically, specimens from the Chincha Islands in Peru, which yielded large crystals, were most important. Currently, new finds rarely appear on the collector's market.
Care and storage
## Cleaning Teschemacherite specimens should absolutely not be cleaned wet. Any contact with water or even humid air leads to its rapid decomposition and destruction. Mechanical cleaning is also inadvisable due to its extreme softness. ## What to Avoid Avoid water, humidity, high temperatures, and direct sunlight. The mineral is unstable at room conditions – at temperatures above 30°C, it begins to decompose, releasing ammonia, carbon dioxide, and water. Even inhaling ammonia fumes can be harmful. ## Storage The only safe storage methods are hermetically sealed containers, preferably with a desiccant (e.g., silica gel). The container should be stored in a cool, dark, and dry place. Due to its instability, it is not suitable for open display.