Jordanite

Chemical formula: Pb₂+₁₄As₃+₆S₂-₂₃

Jordanite is a rare lead arsenic sulfosalt mineral, characterized by its lead-gray color and often iridescent tarnish.

## Characteristics Jordanite is a rare lead arsenic sulfosalt mineral. It typically occurs as well-formed, often tabular or prismatic crystals, which can reach significant sizes. The color of jordanite is typically lead-gray, but the surface of the crystals often exhibits iridescent tarnish, giving them a metallic luster in shades of blue, purple, or green. Crystals can be twinned, forming complex shapes. ## Physical Properties Jordanite has a hardness of 3 on the Mohs scale, making it a relatively soft mineral. It possesses perfect cleavage along {010}. The density of jordanite is 6.33 g/cm³, which is a high value, typical for lead-bearing minerals. The mineral is opaque, and its streak is black. Jordanite's luster is metallic. ## Colors and Varieties The predominant color of jordanite is lead-gray. Iridescent tarnish is often observed on its surface, giving it a characteristic, variable appearance. No specific varieties of jordanite are distinguished, however, the intensity and hue of the iridescence may vary depending on the specimen. ## History and Name Jordanite was described in 1864. Its name comes from H. Jordan, who first discovered this mineral in the Lengenbach mine in Binntal, Switzerland, which remains a classic locality for jordanite to this day. ## Uses Jordanite has no industrial applications due to its rarity and its content of toxic arsenic and lead. It is a mineral valued exclusively by collectors, especially for the aesthetics of its well-formed crystals and their iridescent tarnish.

Properties

Mohs hardness: 3
Luster: Metaliczny
Streak: Black
Density: 6.33
Cleavage: Perfect on {010}.
Fracture: Brak danych
Transparency: Opaque
Crystal system: Monoclinic

Diagnostic features

## Identification Jordanite can be identified by its characteristic lead-gray color, metallic luster, and often present iridescent tarnish on crystal surfaces. Crystals are typically tabular or prismatic. High density is also a diagnostic feature. ## Distinguishing from Similar Minerals Jordanite can be confused with other lead or arsenic sulfides, such as galena or boulangerite. It is distinguished from galena by its lower hardness and lack of perfect cleavage in all three directions, as well as its different crystal habit. It is distinguished from boulangerite by its usually more distinct crystallization and different streak color. ## Crystal Forms Jordanite typically forms well-developed crystals with a tabular or prismatic habit. Twinning is common, giving crystals complex forms. Aggregates can be massive or granular, but single, well-formed crystals are the most prized.

Geological environment

## Genesis Jordanite forms in low-temperature, hydrothermal ore veins, typically in environments rich in lead, arsenic, and sulfur. It often occurs in metamorphic deposits where hydrothermal processes have led to the recrystallization of existing minerals. ## Mineral Associations Jordanite often co-occurs with other sulfides and sulfosalts, such as galena, pyrite, sphalerite, tetrahedrite, realgar, orpiment, as well as with quartz, barite, and calcite. ## Localities The classic and most famous locality for jordanite is the Lengenbach mine in Binntal, Switzerland, where many perfectly formed crystals have been found. Other occurrences include mines in Japan, Romania, and the United States (e.g., Nevada).

Rarity

Uncommon

For collectors

## Quality Criteria The most prized jordanite specimens are well-formed, large crystals with a distinct metallic luster and intense iridescent tarnish. Crystal clarity, absence of mechanical damage, and the overall aesthetic of the form are also important. Specimens from Lengenbach are particularly sought after due to their historical significance and quality. ## Market Prices Jordanite prices vary widely and depend on the size, quality, and aesthetics of the specimen. Small, poorly formed crystals may be available for a few tens of dollars, while large, perfectly formed specimens with intense iridescence, especially those from classic localities, can fetch prices from several hundred to several thousand dollars. ## Popular Localities The most popular and valued locality for jordanite is Lengenbach in Binntal, Switzerland. Specimens from this location are sought after by collectors worldwide due to their historical significance and high quality of crystallization.

Care and storage

## Cleaning Jordanite is a relatively soft mineral, so it should be handled with care. For cleaning, it is best to use a soft, dry brush or a soft-bristled brush to remove dust. For heavier soiling, the surface can be gently wiped with a damp cloth and then immediately dried. ## What to Avoid Avoid using any chemical cleaning agents, acids, or solvents, as they can damage the mineral's surface or cause dulling. Jordanite is susceptible to scratches, so it should not be cleaned with hard tools. Prolonged exposure to direct sunlight can affect the intensity of the iridescent tarnish. Also, avoid sudden temperature changes. ## Storage Jordanite is best stored in enclosed display cases or boxes with soft lining to protect it from dust and mechanical damage. Due to its lead and arsenic content, it is recommended to wash hands after contact with the mineral. Specimens should be displayed away from heat sources and direct light.