Karlditmarite

Chemical formula: Cu₂+₉O₄(PO₄)₂(S₆+O₄)₂

Karlditmarite is an extremely rare copper sulfate and phosphate, forming dark green, acicular crystals in products of volcanic activity.

## Characteristics Karlditmarite is a copper mineral with a complex chemical composition, belonging to the sulfate and phosphate class. It forms very small, prismatic or acicular crystals, rarely exceeding 0.2 mm in length. These crystals occur as radial, sheaf-like, or chaotically arranged aggregates on a substrate of volcanic scoria. The mineral ranges in color from dark green to almost black and exhibits a vitreous luster. ## Physical Properties The mineral's luster is vitreous. In thicker grains, it is opaque, while in thin fragments, it becomes translucent. The fracture is uneven. Due to the small size of the crystals and its rarity, its Mohs hardness and density have not yet been precisely measured. ## Colors and Varieties The mineral occurs in a uniform, dark green to black color. No color or commercial varieties have been distinguished. ## History and Name Karlditmarite was officially recognized as a new mineral species by the International Mineralogical Association (IMA) in 2021. Its name honors Karl von Ditmar (1822–1892), a German geologist and explorer who made significant contributions to the understanding of the geology of the Kamchatka Peninsula in the 19th century, where this mineral was discovered. ## Uses Due to its extreme rarity and microscopic size, karlditmarite has no industrial application. It is solely an object of scientific interest and a valuable acquisition for specialized micromount mineral collectors.

Properties

Luster: Vitreous
Streak: Light green
Cleavage: None
Fracture: Uneven
Transparency: Translucent to Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Identification of karlditmarite is primarily based on its unique locality (fumaroles of Tolbachik volcano), characteristic form of acicular or prismatic crystals forming radial aggregates, and dark green color. However, definitive identification is only possible using advanced analytical methods, such as X-ray diffraction (XRD) and chemical microanalysis (EDS). ## Distinguishing from Similar Minerals Visually, it can be confused with other dark green copper minerals found in the same environment, such as alumoklyuchevskite, piypite, or tenorite. Distinguishing it from these minerals "by eye" is practically impossible and requires specialized studies to confirm its unique chemical composition and crystal structure. ## Crystal Forms Karlditmarite crystallizes in the form of elongated, prismatic to acicular crystals. They typically form aggregates with a radial, sheaf-like structure or chaotic clusters on the surface of the host rock.

Geological environment

## Genesis Karlditmarite is a mineral of volcanic origin. It forms by sublimation from hot gases (exhalations) in high-temperature fumaroles. It crystallizes directly from the gas phase on the surfaces of porous, volcanic scoria at a temperature of approximately 450–500°C. ## Mineral Associations It co-occurs with other fumarolic minerals, such as tenorite, hematite, orthoclase, halite, sylvite, langbeinite, aphthitalite, arcanite, and other rare copper sulfates and arsenates, e.g., alumoklyuchevskite. ## Localities The only known locality of karlditmarite in the world is its type locality: Arsenatnaya fumarole, located on the second cinder cone of the Northern Breakthrough of the Great Tolbachik Fissure Eruption (1975-1976), Tolbachik volcano, Kamchatka, Far East, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria The quality of karlditmarite specimens, being a "micromount" type mineral, is assessed based on several criteria. Samples with rich concentrations of well-formed, sharp, and undamaged crystals are most highly valued. The size of individual crystals is also important – the larger they are, the more valuable the specimen. An additional advantage is the aesthetic arrangement of aggregates on the rock matrix and the presence of rare associated minerals. ## Popular Localities All known specimens come from a single location – the fumarole of Tolbachik volcano in Kamchatka. This locality is inaccessible for commercial extraction, and material is obtained only during rare scientific expeditions.

Care and storage

## Cleaning Karlditmarite specimens are extremely delicate and sensitive. Mechanical cleaning or the use of water or other liquids is not recommended. Any dust can be removed very carefully using a stream of compressed air from a distance or a soft brush, avoiding direct contact with the crystals. ## What to Avoid Contact with water, acids, and other chemicals that can dissolve or damage the mineral should be strictly avoided. As a product of fumarolic sublimation, it is sensitive to changes in humidity and temperature. It should be protected from direct sunlight, which can cause its degradation. ## Storage The safest storage method is to place the specimen in a sealed, closable "micromount" box. This provides protection against dust, moisture, mechanical damage, and stabilizes the microclimate around the sample.

Sources

IMA Mineral List (CNMNC)