- Amblygonite is a lithium-aluminum phosphate mineral with the idealized chemical formula (Li,Na)AlPO₄(F,OH). It is a significant but less common source of lithium, occurring mainly in granitic pegmatites alongside other lithium-bearing minerals such as spodumene, lepidolite, and petalite.
- The name “amblygonite” comes from the Greek amblys (blunt) and gonia (angle), referring to the mineral’s characteristic cleavage angles. Though not as widely used industrially as spodumene, amblygonite has historically played a role in the early extraction of lithium and remains of interest for niche applications and lithium prospecting.
- Structurally, amblygonite is part of the phosphate mineral group, with lithium and aluminum bonded to phosphate groups, and variable amounts of fluorine and hydroxyl substituting in the structure. It commonly contains some sodium, substituting for lithium in natural samples, giving rise to a solid-solution series with the closely related mineral montebrasite (more OH-rich). Crystallizing in the triclinic crystal system, amblygonite typically forms massive to granular aggregates, though well-formed crystals can occur and are often prismatic or tabular. It is generally white, pale yellow, greenish, or bluish in color, with a vitreous to pearly luster and a relatively high density for a lithium mineral.
- Amblygonite is found in rare-element pegmatites, which are coarse-grained igneous rocks enriched in lithium, phosphorus, and volatile elements. Important occurrences include deposits in Brazil, the United States (California and South Dakota), France, Namibia, and Australia. While it was once mined for lithium, its use has declined with the rise of more easily processed ores like spodumene. However, its relatively high lithium content—around 8–10% Li₂O—still makes it economically attractive under certain conditions, especially where spodumene is absent or uneconomical to mine.
- Industrial use of amblygonite is limited due to processing challenges; its phosphate matrix requires different extraction techniques compared to silicate-based lithium ores. Despite this, it can still be used as a minor source of lithium compounds, particularly for ceramics, glass, and specialty chemical applications. In addition to lithium, amblygonite can sometimes contain trace amounts of cesium and fluorine, elements which can be of economic interest in certain deposits.
- In the gem and collector markets, amblygonite occasionally appears as a gemstone, especially when found in transparent, pale-colored crystals. These gem-quality specimens are typically faceted into collectors’ stones, though their relatively low hardness (Mohs 5.5–6) and perfect cleavage make them unsuitable for heavy-wear jewelry. Amblygonite is also appreciated by mineral collectors for its crystal form, luster, and association with other pegmatite minerals.
