Ernstburkeite
Chemical formula: Mg(CH₃S⁶⁺O₃)₂·12H₂O
Ernstburkeite is an organic magnesium sulfate, distinguished by its occurrence as colorless, acicular crystals on burnt shale.
Properties
- Mohs hardness
- 2
- Color
- Colourless
- Luster
- Vitreous
- Streak
- White
- Density
- 1.364
- Cleavage
- Perfect on {100}
- Fracture
- Conchoidal
- Transparency
- Transparent
- Crystal system
- Trigonal
Diagnostic features
## Identification Ernstburkeite can be identified by its characteristic, colorless, acicular crystals forming radial aggregates on dark, burnt shale. A key diagnostic feature is its solubility in water. ## Distinguishing from similar minerals It can be confused with other secondary sulfates formed under similar conditions, such as gypsum or epsomite. It is distinguished from them by its specific crystal form (thin needles) and its occurrence exclusively on products of shale combustion. Accurate identification requires advanced analytical methods (XRD, EDS). ## Crystal forms Crystals are acicular and bladed, elongated along the [001] axis. They form radial or randomly oriented aggregates on the rock surface.
Geological environment
## Genesis Ernstburkeite is a secondary mineral of anthropogenic genesis. It forms as a result of reactions between sulfur oxides (originating from the combustion of pyrite in bituminous shales) and carbonates (dolomite) in the presence of water. It crystallizes from aqueous solutions at temperatures below 50°C on the surface of burnt shale dumps. ## Mineral associations This mineral co-occurs with other products of post-magmatic processes, such as anhydrous calcium sulfate (anhydrite), calcite, dolomite, quartz, and unburnt residues of organic matter and pyrite. ## Localities The only known occurrence of ernstburkeite in the world (type locality) is the lignite mine dump "Glückauf" near the town of Baunatal-Altenritte in Hesse, Germany.
Rarity
Extremely rare
For collectors
## Quality criteria The most prized specimens are those with rich, well-formed, radial aggregates of colorless crystals, clearly contrasting with the dark background of the host rock. The size of the aggregates and the absence of damage to the delicate needles are also important. ## Popular localities The only source of specimens is the type locality in Germany, which makes every specimen from there unique.
Care and storage
## Cleaning Specimens should be cleaned only very carefully, using compressed air to remove dust. Contact with water is absolutely inadvisable, as the mineral is soluble in it. ## What to avoid Avoid water, chemical solutions, ultrasonics, and high humidity, which can lead to crystal degradation. The mineral is very brittle and sensitive to temperature changes. ## Storage Ernstburkeite specimens require storage in dry conditions, preferably in a sealed, airtight box with a desiccant (e.g., silica gel). They should be protected from dust and mechanical damage.