Hokkaidoite

Chemical formula: C<sub>₂₂</sub>H<sub>₁₂</sub>

Hokkaidoite is an extremely rare organic mineral, a natural hydrocarbon known for its intense fluorescence, found in Japanese volcanic fumaroles.

## Characteristics Hokkaidoite is a natural, crystalline form of the polycyclic aromatic hydrocarbon - benzo[ghi]perylene. It occurs as microscopic, thin, platy crystals of a pale yellow color. These crystals most often form small, foliated or scaly aggregates on the surface of the host rock. Due to its organic nature and specific formation conditions, it is a mineral of immense scientific importance. ## Physical Properties The most characteristic feature of hokkaidoite is its strong, yellow to greenish-yellow fluorescence under ultraviolet light (both longwave and shortwave). It is a very soft and delicate mineral. Its hardness and density have not been precisely determined due to the microscopic size and form of crystal occurrence. The luster is described as resinous or greasy. ## Colors and Varieties This mineral occurs exclusively in one color - pale yellow. No color or commercial varieties are known. ## History and Name The name hokkaidoite comes from its discovery location - Hokkaido Island in Japan. It was officially recognized as a new mineral species by the International Mineralogical Association (IMA) in 2022. It was described by a team of Japanese scientists led by Daisuke Nishio-Hamane. ## Uses Due to its extreme rarity and microscopic size, hokkaidoite has no industrial applications. It is solely an object of scientific interest and a valuable acquisition for specialized mineral collectors.

Properties

Luster: Resinous
Streak: Pale yellow
Cleavage: Perfect on {001}
Transparency: Translucent
Crystal system: Monoclinic

Diagnostic features

## Identification The key diagnostic feature of hokkaidoite is its intense yellow or greenish-yellow fluorescence under UV light. Other helpful identification features include its pale yellow color, characteristic form of thin, platy crystals, and specific occurrence environment - volcanic fumaroles. However, definitive identification requires advanced analytical methods, such as Raman spectroscopy or X-ray diffraction. ## Distinguishing from Similar Minerals Hokkaidoite can be confused with native sulfur, which is also yellow and occurs in fumaroles, but sulfur forms different crystal habits and does not exhibit such strong fluorescence. It can also be confused with other rare organic minerals found in similar environments. Final differentiation is almost exclusively possible based on laboratory analysis. ## Crystal Forms Hokkaidoite forms very thin, pliable crystals with a hexagonal or irregular outline, resembling plates or scales. They usually occur as loose, foliated aggregates.

Geological environment

## Genesis Hokkaidoite forms as a result of the sublimation of volcanic gases in high-temperature fumaroles (at temperatures ranging from 200-400°C). It is a product of natural pyrolysis processes of organic matter occurring deep within the Earth's crust, followed by the transport and deposition of volatile compounds in gas emission zones. ## Mineral Associations This mineral co-occurs with native sulfur and other rare organic minerals, which are also polycyclic aromatic hydrocarbons, such as anthracene. ## Localities The only confirmed locality of hokkaidoite in the world is its type locality - the Kumaneshiri area, near Kamishihoro (Kato District) on Hokkaido Island, Japan.

Rarity

Extremely rare

For collectors

## Quality Criteria In the case of such a rare micromineral, the collector's value is primarily determined by the richness of the specimen – meaning the quantity and density of hokkaidoite aggregates on the host rock. Samples with visible, well-formed clusters of platy crystals that exhibit strong and uniform fluorescence are more highly valued. Co-occurrence with other rare organic minerals is an additional asset. ## Popular Localities All known collector specimens come from a single location in the world – the type locality in the Kumaneshiri area on Hokkaido, Japan.

Care and storage

## Cleaning Hokkaidoite specimens are extremely delicate and susceptible to mechanical damage. Wet cleaning or the use of any tools, including brushes, is absolutely discouraged. The only permissible method for removing dust is to very carefully blow it off from a distance using a photographic air blower. ## What to Avoid As an organic mineral, hokkaidoite is sensitive to high temperatures, which can lead to its decomposition. Exposure to direct sunlight and intense UV radiation should be avoided, as, although it causes fluorescence, it can lead to the degradation of the chemical structure in the long term. It should be protected from contact with organic solvents and other chemicals. ## Storage It is recommended to store specimens in closed, padded "perky boxes" that protect against dust, light, and mechanical damage. They should be kept away from heat sources and in an environment with stable, low humidity.

Sources

IMA Mineral List (CNMNC)