Hoelite
Chemical formula: C<sub>14</sub>H<sub>8</sub>O<sub>2</sub>
Hoelite is an organic mineral (anthraquinone), forming rare, yellow coatings and acicular crystals near burning coal seams and in volcanic fumaroles.
Properties
- Mohs hardness
- 1-2
- Luster
- Resinous
- Streak
- Pale yellow
- Density
- 1.41
- Cleavage
- Perfect on {010}
- Fracture
- Uneven
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
Diagnostic features
## Identification Hoelite is identified by its characteristic light yellow color, acicular crystal habit, and unique occurrence environment – near volcanic activity or burning coal dumps. Its low hardness and lightness are also important clues. Yellow fluorescence under UV light is an auxiliary feature. ## Distinguishing from Similar Minerals Hoelite can be confused with native sulfur, which also forms yellow coatings in volcanic environments. However, sulfur usually has a more vitreous luster, is harder, and forms crystals of a different geometry (orthorhombic). Other rare organic minerals may be similar, but usually require advanced studies (e.g., XRD) for unambiguous identification. ## Crystal Forms Hoelite crystals are typically very small, acicular or thin-bladed, elongated along one axis. They often form radial or stellate aggregates, as well as fibrous clusters and thin coatings.
Geological environment
## Genesis Hoelite is a mineral of organic origin, crystallizing from gases through sublimation. It forms under specific conditions, in high-temperature environments. Typical formation sites include volcanic fumaroles and burning coal dumps and seams, where hot gases rich in organic compounds come into contact with cooler air. ## Mineral Associations This mineral co-occurs with other minerals formed under similar conditions. It is most often associated with native sulfur, sal ammoniac (ammonium chloride), and other rare organic minerals. ## Localities The most important hoelite localities worldwide include: - Type locality: the vicinity of the Pyramiden glacier on Spitsbergen, Norway, where it occurs in association with a burning coal seam. - Fumaroles of Mount Vesuvius in Italy. - Burning mine dumps in Pennsylvania (USA) and near Kopeysk in the Southern Urals, Russia.
Rarity
Very rare
For collectors
## Quality Criteria The collector's appeal of hoelite primarily depends on the abundance and development of its crystals. Most valued are specimens with visible, well-formed, acicular crystals forming rich coatings or radial aggregates on a small rock matrix. The intensity and purity of the yellow color also enhance the specimen's value. Due to its rarity, any well-documented specimen is valuable. ## Popular Localities Specimens from the type locality on Spitsbergen and from Vesuvius are the most classic and sought after by collectors specializing in mineral systematics.
Care and storage
## Cleaning Hoelite specimens are extremely delicate and sensitive. Wet cleaning should be avoided. Only very careful dust removal using a soft brush or a photographic air blower is permissible, without touching the fragile crystals. ## What to Avoid Contact with water, chemicals, organic solvents, and detergents must be absolutely avoided. Hoelite is sensitive to elevated temperatures, which can cause sublimation or decomposition. It should be protected from direct sunlight, which can cause fading. ## Storage Specimens should be stored in closed, stable containers (e.g., "micromount" type) to protect them from mechanical damage, dust, and humidity changes. They should be kept in a dry, cool, and dark place.