Latrappite
Chemical formula: Ca₂Fe³⁺Nb⁵⁺O₆
Latrappite is a rare mineral from the perovskite group, an oxide of niobium, calcium, and iron, occurring as small, black, regular crystals.
Properties
- Mohs hardness
- 5.5
- Luster
- Metallic to submetallic
- Streak
- Reddish brown
- Density
- 0
- Cleavage
- Imperfect on {001}
- Fracture
- Uneven to conchoidal
- Transparency
- Opaque
- Crystal system
- Orthorhombic
Diagnostic features
## Identification Latrappite can be identified by its black color, metallic luster, and characteristic, regular crystal forms (cubes, octahedra). It occurs almost exclusively in carbonatites. The reddish-brown streak is also an important diagnostic feature. ## Distinguishing from Similar Minerals It can be confused with other black minerals with a metallic luster, such as magnetite, chromite, or other minerals from the perovskite group. It differs from magnetite by the absence of strong magnetic properties and a different crystal habit. It differs from chromite by its occurrence environment (carbonatites, not ultramafic rocks) and reddish-brown streak (chromite's streak is dark brown). Final distinction from other perovskites often requires advanced chemical analyses (EDS/WDS). ## Crystal Forms Latrappite crystals are typically regular, taking the form of cubes and octahedra, as well as their combinations. They often occur as single, isolated crystals embedded in the rock matrix, mainly in calcite.
Geological environment
## Genesis Latrappite is an igneous mineral, crystallizing in carbonatites – rare igneous rocks composed mainly of carbonates (primarily calcite). It forms in the late stages of crystallization of these intrusions. ## Mineral Associations It most commonly co-occurs with calcite, which constitutes the main mass of the rock. It is also accompanied by other minerals typical of carbonatites, such as apatite, biotite, magnetite, pyrochlore, and niocalite. ## Localities The most important and type locality for latrappite is the Oka carbonatite complex in Quebec, Canada. It has also been found in other carbonatites worldwide, including Lueshe in the Democratic Republic of Congo and on the Kola Peninsula in Russia.
Rarity
Rare
For collectors
## Quality Criteria The most prized specimens by collectors are those with sharp, well-formed, lustrous latrappite crystals, clearly contrasting with a lighter calcite matrix. Crystal size is a key factor – specimens with crystals exceeding 2-3 mm are already considered exceptional. The presence of rarer associated minerals enhances their appeal. ## Popular Localities By far the most desirable and classic specimens come from the type locality – the Oka complex in Quebec, Canada. Specimens from other localities are much rarer on the collector's market.
Care and storage
## Cleaning Latrappite specimens should be cleaned very carefully, using a soft brush to remove dust. Distilled water is permissible, but prolonged soaking should be avoided. It usually occurs as inclusions in calcite, so cleaning methods should be safe for both minerals. ## What to Avoid Contact with acids, which can damage both latrappite and accompanying calcite, must be strictly avoided. The mineral is brittle, so it must be protected from impacts and falls. It should not be heated or subjected to ultrasound. ## Storage Collector specimens of latrappite, due to their small size and brittleness, are best stored in sealed membrane boxes or small perky boxes lined with soft material to prevent mechanical damage.