Ricolite — Banded Serpentine from the American Southwest
Ricolite — Banded Serpentine from the American Southwest
A trade name for green-and-cream banded serpentine cut as cabochons and ornamental carvings
Ricolite is a trade name for a banded serpentine rock found in the south-western United States, particularly in the Burro Mountains of Grant County, New Mexico. The material is characterised by alternating layers of pale and deeper green serpentine — sometimes with cream or near-white bands — and has been worked since the late nineteenth century as an ornamental and lapidary stone. Ricolite is not a distinct mineral species; it is a varietal trade name for a metamorphic rock dominated by serpentine-group minerals.
Composition and formation
The mineralogy of ricolite is principally antigorite and lizardite, the platy and fibrous serpentine-group minerals that form by hydrothermal alteration of olivine-rich ultramafic rocks. The compositional banding reflects original layering in the protolith — typically a serpentinised peridotite or pyroxenite — modified by subsequent shearing and recrystallisation. Variation in iron and magnesium content, with occasional chromium and nickel, drives the colour shift between bands. The hardness sits in the 2.5 to 4 range on the Mohs scale, well below the threshold for ring-stone use.
Source and history
The principal historical source is the Ricolite quarry near Redrock in the Burro Mountains, with related material from other serpentinite occurrences across New Mexico, Arizona, and northern Mexico. The Ricolite Mining Company was active in the late nineteenth and early twentieth centuries and supplied material for ornamental architecture as well as lapidary use. Specimens from the type locality remain in major mineral collections and turn up periodically in the trade in vintage cabochons and beads.
Use and care
The material is worked as cabochons, beads, bookends, small carvings, and decorative inlay. The banded structure is the principal aesthetic feature and is best displayed in flat lapidary cuts with the bands lying parallel to the polished surface. Visual comparison with malachite is sometimes drawn, but ricolite lacks the saturation and the characteristic concentric banding of malachite, and the green is generally cooler and more grey-toned.
Hardness and the typical platy fabric of antigorite-dominated serpentine make ricolite vulnerable to scratching and chipping. Pieces should be cleansed with mild soap and warm water; ultrasonic and steam cleaning should be avoided, as should prolonged exposure to acidic solutions, which attack serpentine readily. Storage away from harder gemstones is sensible.
In the trade
Ricolite is encountered principally in the American lapidary and ornamental-stone trade rather than in mainstream jewellery. Vintage cabochons in silverwork from the south-western jewellery tradition are the commonest form, and freshly mined material is intermittent rather than continuous in supply. The trade name is sometimes applied loosely to other banded serpentines from unrelated localities; the New Mexican origin is the strict referent.