Henrymeyerite
Chemical formula: Ba(Ti⁴⁺₇Fe²⁺)O₁₆
A rare barium, titanium, and iron oxide, forming microscopic, prismatic crystals with a strong, almost adamantine luster.
Properties
- Mohs hardness
- 5-6
- Luster
- Adamantine
- Streak
- Reddish-brown
- Density
- 4.0
- Fracture
- Splintery
- Transparency
- Opaque
- Crystal system
- Tetragonal
Diagnostic features
## Identification Identifying henmeyerite under amateur conditions is practically impossible due to the microscopic size of its crystals. Identification requires advanced laboratory methods, such as EDS or XRD analysis. In collections, it is identified based on a label from a reliable source, describing its occurrence in a specific mineral paragenesis. ## Distinguishing from Similar Minerals It can be confused with other dark, acicular minerals from the hollandite or priderite group, such as priderite or mannardite. Differentiation without specialized chemical analysis is impossible. ## Crystal Forms It forms elongated, prismatic or acicular crystals with a square cross-section, terminated by pyramids. They usually occur as single, dispersed inclusions in other minerals, mainly in phlogopite.
Geological environment
## Genesis Henrymeyerite is a mineral of magmatic origin. It forms in ultrabasic alkaline rocks, such as carbonatites and kimberlites. It crystallizes in the late stages of the formation of these rocks, under conditions of high pressure and temperature. ## Mineral Associations It most commonly co-occurs with phlogopite (in which it forms inclusions), calcite, dolomite, apatite, magnetite, pyrrhotite, and minerals from the hollandite group. ## Localities The most important and well-documented occurrences of this mineral are: - Russia: Kovdor massif on the Kola Peninsula (type locality). - USA: Prairie Creek in Arkansas (in lamproites) and kimberlites in Montana. - Canada: kimberlites in the James Bay area of Quebec.
Rarity
Very rare
For collectors
## Quality Criteria The quality of a henmeyerite specimen primarily depends on the size and development of its crystals, which is a rarity. The most valued specimens are those where the crystals are visible to the naked eye or under slight magnification, and their prismatic form is well-preserved. Color contrast with the surrounding rock matrix (e.g., light phlogopite) also enhances the specimen's attractiveness. ## Popular Localities The most well-known specimens, though still microscopic, come from the type locality in the Kovdor massif in Russia. Specimens from kimberlites in the USA and Canada are also sought after by specialized collectors of rare minerals.
Care and storage
## Cleaning Specimens with henmeyerite, due to the microscopic size of the crystals and their embedding in the rock matrix, usually do not require cleaning. If necessary, compressed air can be used to remove dust. Contact with water and chemical agents that could damage co-occurring minerals should be avoided. ## What to Avoid Ultrasonic cleaners and all acids and solvents should be avoided. The mineral is brittle, so it should be protected from impacts and scratches. It is not sensitive to light, but extreme temperatures should be avoided. ## Storage Specimens should be stored in stable conditions, preferably in a closed display box, to protect them from dust and mechanical damage. Due to the small size of the crystals, it is recommended to include a label with an enlarged photo and precise locality information.