Terranovaite

Chemical formula: NaCaAl₃Si₁₇O₄₀·~₈H₂O

Terranovaite is a hydrated sodium and calcium aluminosilicate, forming colorless, tabular crystals with a pearly luster.

## Characteristics Terranovaite is a mineral from the zeolite group, crystallizing as very thin, colorless, tabular crystals. Individual crystals reach sizes up to 0.5 mm and often form aggregates resembling fans or small rosettes. It is a transparent mineral with a white streak and a characteristic pearly luster on cleavage surfaces. ## Physical Properties This mineral is characterized by a Mohs hardness of approximately 4. It has perfect cleavage in one direction, which, combined with the pearly luster on these surfaces, is its distinguishing feature. The density of terranovaite is approximately 2.26 g/cm³. ## History and Name Terranovaite was first described in 1997 by G. Vezzalini, S. Quartieri, G. Artioli, S. Galli, and A. Alberti. Its name comes from Terra Nova Bay in Antarctica, where Mount Adamson – its discovery site (type locality) – is located. It was approved as a new mineral by the International Mineralogical Association (IMA) under number IMA1996-015.

Properties

Mohs hardness: 4
Luster: Pearly
Streak: White
Density: 2.26
Cleavage: Perfect on {010}
Fracture: Uneven
Transparency: Transparent
Crystal system: Orthorhombic

Diagnostic features

## Identification Characteristic features of terranovaite include its habit as very thin, tabular crystals, often forming fan-like aggregates. The strong, pearly luster on perfect cleavage surfaces and its occurrence in gas vesicles in volcanic rocks are also key. ## Distinguishing from Similar Minerals It can be confused with other tabular zeolites, such as heulandite or stilbite. Distinguishing it requires advanced analytical methods, such as X-ray diffraction (XRD) or chemical analysis (EDS/WDS), as visual features are often insufficient for positive identification. ## Crystal Forms Terranovaite forms very thin, tabular crystals with a hexagonal or pseudo-hexagonal outline. These crystals often combine into fan-like, radial, or spherulitic aggregates.

Geological environment

## Genesis Terranovaite is a hydrothermal mineral. It forms at low temperatures, crystallizing in gas vesicles (amygdales) and fissures in volcanic rocks, such as basalts and dolerites. ## Mineral Associations This mineral co-occurs with other zeolites. At the type locality (Mount Adamson), it was found in association with heulandite, epistilbite, stilbite, mordenite, analcime, laumontite, scolecite, as well as quartz, calcite, and apophyllite. ## Localities The only confirmed and thoroughly described occurrence of terranovaite in the world is its type locality: Mount Adamson, Victoria Land, Antarctica.

Rarity

Extremely rare

For collectors

## Quality Criteria As a "micromount" type mineral, its collector value depends on the quality and development of the microcrystals. Specimens with well-defined, sharp crystals forming aesthetic, fan-like or radial aggregates are most prized. Association with other, contrasting minerals is also important. ## Popular Localities The only source of terranovaite specimens is its type locality in Antarctica, which makes it extremely difficult to obtain and practically unavailable on the commercial market. Specimens from this location primarily have scientific value and are found in institutional collections.

Care and storage

## Cleaning Terranovaite specimens should be cleaned only with great care, using a soft brush to remove dust. Due to its delicacy and small crystal size, wet cleaning or the use of ultrasonic cleaners is not recommended. ## What to Avoid Avoid contact with chemicals, acids, and detergents. As a mineral from the zeolite group, it can dehydrate at elevated temperatures, leading to structural damage. It should be protected from high temperatures and sudden temperature changes. ## Storage It is recommended to store specimens in closed, stable containers (e.g., "micromount" type) to protect them from mechanical damage, dust, and humidity fluctuations. Due to its fragility, it should not be stored in contact with harder minerals.

Sources

IMA Mineral List (CNMNC)