Overview

Andorite is a rare silver–lead–antimony sulfosalt in the andorite–fizelyite series, prized by connoisseurs for its brilliant metallic luster and elegant crystal forms. Typical crystals are steel-gray to black, often striated and highly lustrous, forming thick prismatic blades, blocky prisms, or parallel bundles and sprays. Fine specimens can show sharp terminations and attractive herringbone or “feathered” groupings, commonly on contrasting white to clear quartz or with associated sulfides such as pyrite, sphalerite, or stibnite/jamesonite. It is soft and brittle (Mohs ~3), with a high specific gravity and a tendency to lightly tarnish—factors that make pristine, undamaged pieces both scarce and especially valuable.

The best andorite ever found comes from a handful of classic silver districts in Bolivia and Peru, where pockets produced lustrous, sharply terminated crystals and aesthetic clusters through the 20th century. Fresh, mirror-bright faces, larger crystal size, complete terminations, and display on a good matrix dramatically elevate a specimen’s desirability. Because new production is sporadic, andorite remains a sought-after rarity in sulfosalt-focused collections and in any cabinet aiming to represent the great silver mines of the Andes.

Popularity

Andorite sits firmly in the “connoisseur sulfosalt” category: not abundant, often overshadowed by better-known silver minerals, yet fiercely pursued by specialists. Classic pockets at Bolivia’s San José and Chocaya mines and Peru’s San Genaro and Quiruvilca mines set the benchmark—sleek, reflective crystals with crisp striations and attractive groupings. These finds circulated widely among collectors in the 1960s–1990s and continue to define top quality.

Today, fresh discoveries are uncommon. As a result, fine older pieces—especially on good quartz matrix or in large, damage-free crystals—command strong prices and trade quickly when they appear. Collectors also appreciate andorite’s historical significance in the Andean silver story and its aesthetic versatility: from stout, graphite-luster prisms to elegant feathery aggregates sparkling against white quartz. Because the supply pipeline is thin, choice pieces enjoy enduring, even rising, demand.

Top Collecting Localities

Below are renowned sources known for producing distinctive andorite specimens. Only localities with verified IDs are included.

San José Mine, Bolivia

Oruro’s San José Mine is arguably the most celebrated andorite source. Classic specimens feature lustrous, striated prisms and thick blades—often in radiating sprays or stair-stepped clusters—on quartz. The best have mirror-bright, gunmetal faces and crisp terminations, sometimes accompanied by pyrite, sphalerite, or tetrahedrite. These crystals display superbly with bright contrast and remain reference pieces for form and luster. Large, undamaged matrix specimens are uncommon and highly coveted.

Collector’s Guide

Evaluating Specimen Quality

• Luster and freshness

  • Top andorite dazzles with a bright, mirror-like metallic luster. Fresh, unoxidized faces are ideal; slight natural iridescence can be attractive, but dull, matte or heavily tarnished surfaces reduce impact.
  • Look at how evenly the luster reflects across faces—uniform shine suggests minimal etching and better preservation.

• Crystal size and form

  • Choice crystals range from stout blocky prisms to elongate bladed forms, commonly with fine striations. Sharp, complete terminations are a major plus.
  • Parallel-growth bundles and radiating sprays can be spectacular, especially when well-balanced on matrix. “Feathery” aggregates with well-defined individual terminations are more desirable than matted, broken masses.

• Aesthetics and matrix

  • Strong contrast on white/clear quartz or drusy quartz is highly prized. Associations with pyrite, sphalerite, or other sulfosalts add context and interest.
  • Composition matters: a dominant main crystal or a harmonious fan of crystals with height and directionality will display better than a jumbled cluster.

• Condition

  • Andorite is brittle and soft (Mohs ~3). Check edges and tips closely for nicks; crisp, unchipped terminations command a premium.
  • Avoid specimens with pervasive micro-chipping that kills the luster. Minor, well-hidden contacts are acceptable if the overall presentation shines.

• Color and patina

  • Fresh steel-gray to black is classic. A light, natural patina can add character, but heavy oxidation or “chalky” alteration detracts.
  • Beware of overly uniform, inky-black surfaces on older pieces—occasionally, coatings or treatments are used to mask wear (see below).

• Rarity and provenance

  • Locality matters. San José and Chocaya (Bolivia) and San Genaro/Quiruvilca (Peru) set the high bar. Good labels and documented provenance add confidence and value.

Detecting Repairs or Treatments

• Repairs

  • Crystal or matrix reattachments are possible due to brittleness. Inspect bases and junctions under 10x for straight glue lines, filamentous residue, or misaligned striations.
  • UV (LW) can sometimes reveal fluorescing epoxies along seams.

• Surface coatings and “re-blackening”

  • Light waxes or oils may be applied to deepen luster or slow tarnish. Coated areas can look slightly “plasticky,” feel slick, or show uneven glare.
  • Less commonly, chemical patination (“re-blackening”) is used to hide wear. Telltales include overly uniform color in recesses, chemical odors, or darkened matrix minerals that should not be affected.

• Polishing

  • Polished or lightly “buffed” edges lose natural micro-growth texture. Natural faces typically retain fine striations and micro-topography; over-polished faces look unnaturally smooth.

Ask dealers about any restoration—solid disclosures are standard practice for high-end sulfosalts.

Care and Storage

Andorite, like many sulfosalts, benefits from careful, dry storage and gentle handling.

• Handling

  • Mohs ~3 and brittle—handle over a padded surface and avoid touching sharp tips.
  • Support matrix pieces with both hands; don’t torque clusters or “test” flexibility.

• Environment

  • Store in a stable, low-humidity environment (ideally 35–45% RH). Use closed cabinets with fresh silica gel or molecular sieves; consider humidity indicators.
  • Avoid prolonged direct sunlight and heat sources; temperature swings can exacerbate micro-fracturing and tarnish.

• Cleaning

  • Dust gently with a soft air bulb or very soft brush. If needed, a light wipe with a barely damp microfiber cloth (distilled water) is acceptable—dry immediately.
  • Do not use acids, ultrasonic cleaners, steam, or aggressive detergents—these can damage andorite and/or its matrix and may accelerate alteration.
  • If fingerprints dull the luster, a drop of isopropyl alcohol on a cotton swab followed by immediate drying can help; test a tiny area first.

• Tarnish management

  • Mild, even patina is normal. Avoid abrasive polishing, which removes natural surfaces and value.
  • To slow tarnish, keep pieces dry and away from sulfur-bearing materials, wood off-gassing, or carboard with acids; archival foams and inert plastics are preferred.

• Health and safety

  • Contains lead and antimony; wash hands after handling and keep out of reach of children or pets. Avoid creating or inhaling dust.

Following these simple practices will preserve the brilliant luster and sharp forms that make andorite such a rewarding mineral to collect.