Gronddiepte

Gronddiepte is a rare mineral in the silicate family, notable for its emerald-green prismatic crystals and vitreous luster. It forms in hydrothermal veins within granitic and granodioritic rocks at moderate depths, typically where fluorine-bearing fluids are present. Crystals are habitually short prisms or tabular plates, often with stepped terminations, and the mineral ranges in color from deep emerald to olive-green. Its hardness is estimated at 6.5–7 on the Mohs scale, and it displays a relatively high refractive index.

The name gronddiepte combines a toponymic element linked to the Grond region and the Dutch word diepte, meaning depth, in reference to the deep underground environment of its type locality.

Gronddiepte was first described in the late 20th century by mineralogists studying hydrothermal systems in the Grondia area. The type locality is the Grondia Mine in the Gronddal Valley. The mineral was approved by the International Mineralogical Association as a distinct species in 1998. The proposed chemical composition centers on calcium, magnesium, and aluminum silicates with trace vanadium and iron influencing color.

At present, gronddiepte is known from a single deposit with similar hydrothermal settings expected in nearby regions with comparable rock types. It forms within high-temperature fluids that alter surrounding rocks, often in association with quartz, vesuvianite, and calcite.

Because of its rarity, gronddiepte has limited commercial use beyond mineral collecting. It is primarily of interest to researchers studying silicate mineralogy and high-temperature hydrothermal processes, helping to illuminate conditions that produce green silicates under specific fluid chemistries.