Shandite
Chemical formula: Pb<sub>2</sub>Ni<sub>3</sub>S<sub>2</sub>
Shandite is a rare, metallic mineral with a tin-bronze color, found in serpentinites and ultramafic igneous rocks.
Properties
- Mohs hardness
- 4
- Luster
- Metallic
- Streak
- Black
- Density
- 8.93
- Cleavage
- Perfect on {0001}
- Fracture
- Uneven
- Transparency
- Opaque
- Crystal system
- Trigonal
Diagnostic features
## Identification Identifying shandite with the naked eye is practically impossible due to the very small grain sizes. Identification requires advanced laboratory methods, such as reflected light analysis (ore microscopy), where it exhibits characteristic anisotropy, and chemical analysis (EDS/WDS) to confirm its composition (presence of Ni, Pb, and S). ## Distinguishing from similar minerals It can be confused with other metallic sulfides of similar color, such as pentlandite, heazlewoodite, or pyrite. Differentiation is almost exclusively possible based on chemical and crystallographic analysis. In reflected light, it differs from heazlewoodite by the absence of pleochroism. ## Crystal forms It forms tiny, hexagonal or trigonal lamellae and plates, as well as irregular grains and aggregates. Crystals are usually too small for their form to be visible without a microscope.
Geological environment
## Genesis Shandite is a low-temperature hydrothermal mineral. It forms during the serpentinization processes of ultramafic rocks, such as dunites and peridotites. It forms in veins cutting through these rocks. ## Mineral associations It most commonly co-occurs with heazlewoodite, pentlandite, magnetite, chromite, awaruite, millerite, as well as minerals from the serpentine group (antigorite, lizardite) and carbonates (magnesite, dolomite). ## Localities Key worldwide localities include Trial Harbour in Tasmania (Australia), from which the type material originates; the Dundonald area in Ontario (Canada); the magmatic complex on the Kola Peninsula (Russia); nickel deposits in Kraubath an der Mur in Styria (Austria), and in Val Malenco in Italy.
Rarity
Very rare
For collectors
## Quality criteria The quality of a shandite specimen is primarily assessed based on the abundance of its occurrence in the host rock and the confirmation of its identity through analysis. Since the crystals are microscopic, their form is not a key criterion. The most valued samples are those from well-documented, classic localities where shandite forms aggregates visible under magnification in association with other rare nickel sulfides. ## Popular localities Specimens from the type locality in Tasmania and from the Canadian province of Ontario are the most well-known among collectors and scientists.
Care and storage
## Cleaning Shandite specimens, due to their occurrence as fine inclusions in the host rock, usually do not require cleaning. If necessary, only use compressed air to remove dust. ## What to avoid Avoid contact with acids and other chemicals that may react with sulfides. The mineral is brittle, so protect it from impacts and scratches. Do not clean it with ultrasonics. ## Storage Specimens should be stored in stable conditions, away from moisture, to prevent potential oxidation. It is best to keep them in sealed display boxes or cabinets to protect them from dust and mechanical damage.