Guide
Londonite specimens for sale
15 for sale · $250–$4,000 USD
40 in the gallery
Londonite is a complex borosilicate mineral that contains cesium, potassium, rubidium, aluminum, beryllium, boron, and oxygen. It typically forms as transparent to translucent crystals with a pale to yellow-brown tint and a vitreous to resinous luster. The mineral’s cubic or near-cubic habit and its rare, intricate chemical composition make it a striking addition to a cabinet of mineral specimens, especially when well-formed crystals are available.
- Formula
- (Cs,K,Rb)Al4Be4(B,Be)12O28
- Rarity
- Rare
- Stability
- Stable
- Collector interest
- Very High Interest
- Classification notes
- Borate, tectoborate; rhodizite group
Key characteristics
- Crystal system
- isometric
- Mohs hardness
- 8
- Specific gravity
- 3.34–3.42
- Luster
- vitreous
- Transparency
- transparent, translucent
- Color
- colorless, white, gray, yellow, pink
- Streak
- white
- Cleavage
- none
- Fracture
- conchoidal, uneven
- Crystal habit
- dodecahedral, equant, granular, massive
Buy Londonite specimens
View all 15Where Londonite is found
Top localities
- Vakinankaratra6 specimens
- Antsirabe1 specimen
- Antsongombato gem mine, Antsentsindrano1 specimen
- Ampanivana Area1 specimen
Guides
All guidesAbout Londonite
Notable specimens of Londonite have come from Madagascar, a country known for its diverse pegmatite deposits that yield exotic alkali- and beryllium-rich minerals. Collectors prize Londonite for its rarity and the challenge of acquiring well-crystallized examples that clearly display its complex crystal chemistry. The mineral’s unusual combination of alkali metals and borosilicate framework offers a compelling look into borosilicate mineralogy and the behavior of complex alkali-bearing phases in pegmatites.
