Kladnoite
Chemical formula: C₆H₄(CO)₂NH
Kladnoite is a rare organic mineral – a naturally occurring form of phthalimide, found in burning mine dumps.
Properties
- Mohs hardness
- 1-2
- Color
- Yellow, white, colourless
- Luster
- Vitreous
- Streak
- White
- Density
- 0
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Transparent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Kladnoite is primarily identified by its occurrence – it is found almost exclusively in gas exhalation zones on burning mine dumps. Characteristic features include small, colorless or yellowish, tabular crystals with a vitreous luster, forming efflorescences. It is very soft and light. ## Distinguishing from Similar Minerals It can be confused with other organic minerals found in similar environments, such as salammoniac (ammonium chloride) or native sulfur. However, salammoniac has a different, salty taste and often forms dendritic aggregates. Sulfur has an intense yellow color and a characteristic odor when heated. Definitive differentiation requires advanced analytical methods. ## Crystal Forms Kladnoite crystallizes in the monoclinic system, forming very small, thin, tabular or lath-like crystals. It most often occurs as fine-grained aggregates, efflorescences, and thin crusts on fragments of burnt rocks.
Geological environment
## Genesis Kladnoite is a secondary mineral of anthropogenic genesis. It forms as a result of sublimation and resublimation of volcanic gases (fumaroles) on burning coal dumps. It forms in zones with temperatures ranging from 50 to 150°C due to the reaction of ammonia with phthalic anhydride, which are products of the thermal decomposition of organic matter contained in coal. ## Mineral Associations It most often co-occurs with other minerals typical of burning dump environments, such as native sulfur, salammoniac, realgar, and orpiment. ## Localities The most important and classic localities for this mineral are in the Czech Republic, in the Kladno region (Schoeller mine) and Radvanice (Ostrava). It is also known from burning dumps in Pennsylvania (USA), near Świętochłowice and Radlin in Poland, and from several locations in Germany (e.g., Anna mine in Alsdorf).
Rarity
Very rare
For collectors
## Quality Criteria Specimens with rich, well-visible crystalline efflorescences on a stable substrate (matrix) are most valued by collectors. The size and abundance of crystals are important, although they rarely exceed a millimeter. Specimens from the type locality (Kladno, Czech Republic) or from well-documented sites have higher value. Purity and lack of damage to delicate crystals are crucial. ## Popular Localities Classic and most sought-after specimens come from dumps in Kladno and Ostrava in the Czech Republic. Increasingly, materials from burning dumps in Poland (Upper Silesia) and Pennsylvania in the USA are also appearing on the market.
Care and storage
## Cleaning Kladnoite specimens should generally not be wet cleaned. Due to its water solubility and high delicacy, the only safe method for dust removal is to use a soft brush or carefully blow it off with compressed air from a distance. ## What to Avoid Contact with water, alcohol, and other solvents must be strictly avoided. The mineral is sensitive to high temperatures, which can cause its sublimation (transition from solid to gas). It should be protected from moisture and direct sunlight. ## Storage Kladnoite specimens should be stored in dry conditions, preferably in tightly sealed containers (e.g., "membrane box" type or boxes with a desiccant). Storage at a stable room temperature, away from heat and light sources, is crucial for preserving specimens in good condition.