Yurmarinite

Chemical formula: Na₇(Fe₃+,Mg,Cu₂+)₄(As₅+O₄)₆

Yurmarinite is a rare sodium, iron, magnesium, and copper arsenate, forming tiny, brown crystals in volcanic exhalation products.

## Characteristics Yurmarinite is a complex arsenate belonging to the alluaudite group. It forms small, prismatic or tabular crystals, reaching up to 0.2 mm in size. It most commonly occurs as granular aggregates and clusters up to 1 mm in size, growing on a substrate or filling small cavities in volcanic rock. ## Physical Properties This mineral is characterized by a vitreous luster. It is transparent in small grains and fragments. Hardness has not been determined. Its calculated density is 3.93 g/cm³. ## Colors and Varieties Yurmarinite is dark brown to reddish-brown in color. No varieties have been distinguished. ## History and Name The mineral was approved by the International Mineralogical Association (IMA) in 2011 under number IMA2011-057. Its name honors Yuri Borisovich Marin (born 1939), a Russian mineralogist and petrologist, professor at the Saint Petersburg Mining University, specializing in the study of granite pegmatites and gemstone deposits. ## Applications Due to its extreme rarity and microscopic crystal sizes, yurmarinite has no commercial or industrial applications. It is solely an object of scientific research and a valuable acquisition for specialized micromineral collectors.

Properties

Luster: Vitreous
Streak: Light brown
Density: 3.93
Cleavage: None
Transparency: Transparent
Crystal system: Trigonal

Diagnostic features

## Identification Identification of yurmarinite based on visual characteristics is practically impossible. The key factors are its locality (Arsenatnaya fumarole on Tolbachik volcano) and co-occurrence with other rare arsenates. Its characteristic brown color and form of small, granular aggregates are distinctive. Definitive identification requires advanced analytical methods, such as chemical composition analysis (EDS) and X-ray diffraction (XRD). ## Distinguishing from Similar Minerals Yurmarinite can be confused with many other brown arsenate minerals found in the same environment, such as johillerite, eryklyxite, or other minerals from the alluaudite group. Distinguishing them from each other is only possible through detailed laboratory analyses. ## Crystal Forms It forms short, prismatic or tabular crystals, which most often grow together into granular aggregates and crusts.

Geological environment

## Genesis Yurmarinite forms as a result of volcanic activity, crystallizing directly from hot gases (sublimates) in a fumarolic environment. Its genesis is associated with exhalative processes occurring at high temperatures. ## Mineral Associations This mineral occurs in association with other fumarolic minerals. The most common associations include hematite, tenorite, sanidine, arsenobismite, johillerite, dmitryivanovite, eryklyxite, and hatrurite. ## Localities The only confirmed locality of yurmarinite in the world is its type locality – Arsenatnaya fumarole, located on the second cinder cone of the Northern Breakthrough of the Great Fissure Eruption of Tolbachik volcano in Kamchatka, Russia.

Rarity

Extremely rare

For collectors

## Quality Criteria For such a rare micromineral, the collector's value is primarily determined by the richness of the specimen – the quantity and size of yurmarinite clusters on the rock matrix. An additional advantage is the presence of well-formed, even microscopic, crystals and association with other rare minerals from this locality. ## Popular Localities All known yurmarinite specimens come from a single location in the world – Arsenatnaya fumarole on Tolbachik volcano in Kamchatka. This locality is highly prized by collectors specializing in fumarolic minerals.

Care and storage

## Cleaning Yurmarinite specimens are extremely delicate and usually microscopic in size. Wet cleaning is not recommended. Any dust can be removed very carefully with a soft brush or a stream of compressed air from a safe distance. ## What to Avoid Avoid contact with water, acids, and other chemicals. As a fumarolic mineral, it may be unstable in conditions of high humidity or sudden temperature changes. It should be protected from direct sunlight. ## Storage The safest storage method is to place the specimen in a sealed plastic "micromount" box, which protects it from dust, mechanical damage, and changes in ambient humidity.

Sources

IMA Mineral List (CNMNC)