Laitakarite

Properties

Mohs hardness

2

Luster

Metallic

Streak

Grayish black

Density

8.12

Cleavage

Perfect on {0001}

Fracture

Micaceous

Transparency

Opaque

Crystal system

Trigonal

Diagnostic features

## Identification Laitakarite is identified by its metallic luster, tin-white color, very low hardness (2 on the Mohs scale), and perfect cleavage, which causes thin lamellae to separate. Its high density is also characteristic. It occurs as small, lamellar or scaly aggregates. ## Distinguishing from Similar Minerals It can be confused with other bismuth selenides and sulfides, such as bismuthinite, guanajuatite, or joséite. Differentiation requires advanced analytical methods, such as chemical analysis (EDS/WDS) to determine the bismuth-to-selenium and sulfur ratio, or X-ray diffraction (XRD) to confirm the crystal structure. Visually, it is practically indistinguishable from some of them. ## Crystal Forms Crystals are rare and usually take the form of thin, hexagonal tablets. Most commonly, it is found as lamellar, scaly, or granular aggregates embedded in the host rock.

Geological environment

## Genesis Laitakarite is a hydrothermal mineral, forming under medium and high-temperature conditions. It forms in ore veins and in skarns, which are metamorphic rocks formed at the contact of magmatic intrusions with carbonate-rich sedimentary rocks (e.g., limestones). ## Mineral Associations It often co-occurs with other ore minerals. In its type locality (Orijärvi, Finland), it was found in association with chalcopyrite, pyrite, pyrrhotite, cordierite, anthophyllite, and quartz. In other localities, it is accompanied by native bismuth, bismuthinite, arsenopyrite, galena, sphalerite, as well as other rare selenides and tellurides. ## Localities The most important and confirmed laitakarite localities worldwide include: - Orijärvi quarry in Laitakari, Finland (type locality). - Falun Mine, Dalarna, Sweden. - Boliden Mine, Västerbotten, Sweden. - Tsumo deposit, Shimane Prefecture, Japan. - Kidd Creek Mine, Ontario, Canada.

Rarity

Rare

For collectors

## Quality Criteria The collectible appeal of laitakarite primarily depends on the abundance of its occurrence on the rock matrix and the size of the aggregates. Since it is a rare mineral and usually occurs in small clusters, specimens with clearly visible, larger lamellae or grains are more valued. Exceptionally rare, well-formed crystals, even if microscopic, achieve the highest value. Association with other rare minerals is also important. ## Popular Localities Specimens from the type locality in Finland (Orijärvi) have historical significance. However, the most well-known and prized collectible specimens come from Swedish mines, such as Falun and Boliden, where laitakarite formed richer concentrations. Specimens from the Kidd Creek mine in Canada are also known among specialists.

Care and storage

## Cleaning Laitakarite specimens should be cleaned with the utmost care due to their softness and perfect cleavage. The safest method is to use compressed air to remove dust. Any mechanical cleaning, even with a soft brush, risks scratching or delaminating the mineral. Wet cleaning is not recommended. ## What to Avoid Avoid contact with chemicals, especially acids, which can react with the mineral. Due to its low hardness, it must be protected from scratches by harder minerals. Ultrasonic cleaners should also be avoided, as they could damage the delicate structure. ## Storage Laitakarite should be stored separately, in a closed display box, away from harder minerals. It is best placed on a soft lining to prevent mechanical damage. It is not sensitive to light, but should be protected from moisture and contaminants.

Sources

• IMA Mineral List (CNMNC)