Transjordanite

Chemical formula: Ni<sub>₂</sub>P

Transjordanite is an extremely rare nickel phosphide, found as microscopic, metallic inclusions in pyrometamorphic rocks.

## Characteristics Transjordanite is a mineral with a metallic appearance, occurring as very small, rounded or irregular grains, usually not exceeding 50 micrometers in size. It is observed as inclusions within other minerals. Its surface on a fresh fracture ranges from creamy-white to yellowish, but it quickly tarnishes and darkens upon exposure to air. ## Physical Properties This mineral is characterized by a strong, metallic luster. It is opaque. Due to the microscopic size of its grains, precise determination of hardness and density is difficult; these values are estimated based on the properties of its synthetic analogue (Ni₂P). ## History and Name Transjordanite was discovered in rocks of the Hatrurim Formation in the Daba-Siwaqa region of Transjordan (now Jordan). Its name comes from the historical name of the region where the type locality is situated. The mineral was described and approved by the International Mineralogical Association (IMA) in 1996. ## Uses Transjordanite has no industrial application due to its extreme rarity and microscopic size. It is solely of scientific importance and is an object of interest for specialized collectors of rare minerals.

Properties

Mohs hardness: 6-7
Luster: Metallic
Streak: Black
Density: 7.35
Cleavage: None
Fracture: Uneven
Transparency: Opaque
Crystal system: Hexagonal

Diagnostic features

## Identification Identification of transjordanite is impossible without advanced laboratory techniques. It requires analysis using a scanning electron microscope (SEM) with an EDS analyzer to confirm its chemical composition (nickel and phosphorus). In reflected light microscopy, it exhibits a creamy-yellow color and strong luster. ## Distinguishing from Similar Minerals It can be confused with other rare nickel phosphides, such as niquelfosfide (Ni,Fe)₃P, from which it differs in the nickel-to-phosphorus ratio. Visually, it is indistinguishable from other microscopic metal sulfides and phosphides without specialized analysis. ## Crystal Forms Transjordanite forms very fine, rounded or irregular grains and aggregates. Well-formed crystal faces are not observed.

Geological environment

## Genesis Transjordanite forms under pyrometamorphic conditions, meaning rock alteration due to very high temperatures, often associated with the spontaneous combustion of underground bituminous deposits. It occurs in rocks of the Hatrurim Formation (also known as the "Mottled Zone"), which are rich in phosphates and sulfides. ## Mineral Associations This mineral co-occurs with calcite, gypsum, and other rare minerals formed in the same environment, such as murashkoite, barringerite, niquelfosfide, as well as minerals from the apatite group and chromian spinel. ## Localities The only confirmed occurrence of transjordanite in the world is its type locality in the Daba-Siwaqa region, northeast of Amman in Jordan. This is an area where rocks of the Hatrurim Formation are found.

Rarity

Extremely rare

For collectors

## Quality Criteria Due to the microscopic nature of the mineral, its collector value is not assessed based on typical criteria such as color or form. The most important factor is the abundance of transjordanite grains in the host rock and the confirmation of its identity through scientific analysis. A specimen is valuable if it contains numerous, clearly visible aggregates under the microscope, preferably in association with other rare minerals from this locality.

Care and storage

## Cleaning Specimens containing transjordanite should generally not be cleaned. The mineral occurs as microscopic inclusions in the host rock, and any attempt at mechanical or chemical cleaning may destroy or remove it. If dust removal is necessary, a gentle stream of compressed air can be used. ## What to Avoid Contact with chemicals, acids, and even water, which can accelerate the oxidation process, should be strictly avoided. The mineral is sensitive to air, which causes it to tarnish, so its exposure should be limited. ## Storage Specimens containing transjordanite are best stored in closed, airtight containers, such as "perky boxes," to minimize contact with moisture and oxygen from the air. Storage in a dry place is crucial for preserving the mineral's appearance.

Sources

IMA Mineral List (CNMNC)