Svornostite-(NH_4_)

Chemical formula: (N₃-H₄)₂Mg(U₆+O₂)₂(S₆+O₄)₄(H₂O)₈

Svornostite-(NH₄) is a very rare, water-soluble uranyl sulfate, occurring as small, yellow tabular crystals.

## Characteristics Svornostite-(NH₄) is a hydrated uranyl, magnesium, and ammonium sulfate. It forms very small, thin, tabular crystals, not exceeding 0.2 mm in size, which often occur in radial or randomly oriented aggregates. It is a secondary mineral, forming under specific conditions in uranium mines. ## Physical Properties The crystals exhibit intense, yellowish-green fluorescence under ultraviolet light (both long-wave and short-wave). The mineral is soft and brittle. Due to the presence of the ammonium ion, it is water-soluble. ## Colors and Varieties Svornostite-(NH₄) has a characteristic, light yellow color. No varieties have been distinguished. ## History and Name The mineral's name comes from the Czech word "svornost" meaning "concord" or "harmony", which is the historical name of the mine where it was discovered (Svornost mine in Jáchymov). It was officially described and approved as a new mineral by the International Mineralogical Association (IMA) in 2016 (IMA2016-064). Its discoverers are Jakub Plášil and his research team. ## Uses Due to its extreme rarity, small crystal size, and instability, svornostite-(NH₄) has no practical applications. It is solely an object of scientific and collecting interest for specialized collectors of uranium minerals.

Properties

Mohs hardness: 2
Luster: Vitreous
Streak: Light yellow
Density: 3.12
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Orthorhombic

Diagnostic features

## Identification Key diagnostic features include its light yellow color, tabular form of very small crystals, intense yellowish-green fluorescence under UV light, and occurrence in paragenesis with other secondary uranium minerals. Water solubility is a characteristic feature, but testing it destroys the sample. ## Distinguishing from Similar Minerals It can be confused with other secondary uranyl sulfates, such as zippeite, johannite, or uranopilite. Final differentiation requires advanced analytical methods, such as X-ray diffraction (XRD) or Raman spectroscopy, due to the very similar visual appearance of these minerals. ## Crystal Forms Svornostite-(NH₄) forms thin, tabular crystals with a rhombic or hexagonal outline. These crystals rarely occur individually, most often forming small, radial aggregates or disordered clusters on the surface of the host rock.

Geological environment

## Genesis It is a secondary mineral, formed as a result of weathering processes (oxidation) of primary uranium ores (mainly uraninite) in an environment rich in sulfates and ammonium ions. Its formation is associated with the activity of mine waters in the oxidation zone of uranium deposits. Ammonium ions can originate from the decomposition of organic matter or from materials used in mining processes. ## Mineral Associations It most often co-occurs with gypsum, adolfpaterite, amarantite, halotrichite, kornelite, epsomite, zippeite, and other secondary uranyl sulfates. ## Localities The only confirmed locality of this mineral in the world (type locality) is the Svornost mine in Jáchymov, Karlovy Vary Region, Czech Republic.

Rarity

Extremely rare

For collectors

## Quality Criteria The collecting appeal of a specimen depends on the richness and aesthetics of the crystal aggregates on the rock matrix. Most valued are samples with clearly formed, though still microscopic, crystals forming dense aggregates of an intense yellow color. The size of the matrix itself and the presence of associated minerals are also important. ## Popular Localities The only source of specimens is the historic Svornost mine in Jáchymov (Czech Republic). Material from this locality is extremely sought after by collectors specializing in systematic minerals and uranium minerals.

Care and storage

## Cleaning The mineral must not be wet-cleaned, as it is water-soluble. Any attempts to clean it with liquids, including distilled water, will lead to its destruction. Specimens should only be cleaned using compressed air or a very soft brush. ## What to Avoid Contact with water and all other liquids must be strictly avoided. The mineral is sensitive to changes in humidity – it can dehydrate and disintegrate under its influence. It should be protected from high temperatures and direct sunlight. As a uranium mineral, it is radioactive and requires careful handling. ## Storage Svornostite-(NH₄) specimens must be stored in sealed, airtight containers (e.g., "perky box" type) or under controlled, low humidity conditions. It is best to keep it in a stable environment, away from heat and light sources, in a specialized radioactive mineral display case.