Hainite-(Y)

Chemical formula: Ca₂(CaY)Na(NaCa)Ti₄+(Si₂O₇)₂(OF)F₂

Hainite-(Y) is a very rare mineral from the sorosilicate group, distinguished by its complex chemical composition with the presence of titanium and yttrium.

## Characteristics Hainite-(Y) is an extremely rare mineral belonging to the sorosilicates of the rosenbuschite group. It forms prismatic, acicular, or bladed crystals, usually small, reaching up to 2 mm in length. Most often, it occurs in the form of radial or tangled aggregates. It is a transparent to translucent mineral with a vitreous luster. ## Physical properties The mineral is characterized by a Mohs hardness of approximately 5. Its density is relatively high, around 3.55 g/cm³. It exhibits perfect cleavage in one direction. ## Colors and varieties Hainite-(Y) is usually colorless, white, pale yellow, or light brown. No named varieties are known. ## History and name The mineral's name refers to its chemical composition – the dominance of yttrium (Y) in a specific structural position – and its relation to the older, similar mineral hainite. It was approved as a new mineral species by the International Mineralogical Association (IMA) in 2000 under the number IMA2000-014. It was described by Ole V. Petersen and co-workers based on material from the Ilimaussaq igneous complex in Greenland.

Properties

Mohs hardness: 5
Luster: Vitreous
Streak: White
Density: 3.55
Cleavage: Perfect on {100}
Fracture: Uneven
Transparency: Transparent to translucent
Crystal system: Triclinic

Diagnostic features

## Identification Identification of hainite-(Y) under amateur conditions is practically impossible and requires advanced analytical techniques such as X-ray diffraction (XRD) and chemical microanalysis (EDS/WDS). Its occurrence in a specific geological environment (nepheline syenites) and co-occurrence with other rare minerals can be an indicator. ## Distinguishing from similar minerals It can be confused with other acicular silicates found in the same environment, such as eudialyte, lorenzenite, or members of the rosenbuschite group. Definitive differentiation is only possible based on chemical and crystallographic analysis. ## Crystal forms Crystals are prismatic, elongated, and often flattened, forming acicular or bladed shapes. They usually occur as radial or haphazardly arranged aggregates embedded in the host rock.

Geological environment

## Genesis Hainite-(Y) is a magmatic mineral. It forms in the late stages of crystallization within pegmatites associated with alkaline nepheline syenites. ## Mineral associations It co-occurs with other minerals typical of this environment, such as eudialyte, lorenzenite, nepheline, microcline, aegirine, rinkite, nacareniobsite-(Ce), and vitusite-(Ce). ## Localities The only confirmed and thoroughly described occurrence (type locality) is the Ilimaussaq alkaline complex in southern Greenland. This is one of the world's most famous localities for rare alkaline minerals.

Rarity

Very rare

For collectors

## Quality criteria As a "micromount" type mineral, specimens with well-formed, sharp, and undamaged crystals, forming aesthetic, radial aggregates, have the greatest collector value. Contrast with the surrounding rock (matrix) and the presence of rare associated minerals are also important. The clarity and size of individual crystals, even if they are only 1-2 mm, significantly increase the specimen's value.

Care and storage

## Cleaning Due to the rarity and delicacy of specimens, cleaning with compressed air is recommended solely for dust removal. Contact with water and chemical agents should be avoided. ## What to avoid Avoid ultrasonic cleaners, steam cleaners, and all acids and bases. The mineral is sensitive to sudden temperature changes. Due to the small size of its crystals, it is very brittle and susceptible to mechanical damage. ## Storage Hainite-(Y) specimens should be stored in stable conditions, away from dust and moisture, preferably in sealed "micromount" boxes. They should be protected from vibrations and impacts.

Sources

IMA Mineral List (CNMNC)