Percentiliitti

Percentiliitti is a rare type of silicate mineral that is classified as a borosilicate mineral. It is composed of sodium and lithium silicates and has a distinctive chemical composition, Na2Li3Ti(Si2O6)(O,OH) series. The mineral was first discovered in 1953 in the Rannila pegmatite deposit in Finland.

Percentiliitti was named due to its position in the mineralogical table of silicates, specifically between the series of borosilicates and the series of silicates. The mineral occurs as small, tabular crystals or flattened grains, typically ranging in size from a few millimeters to a few centimeters.

Structurally, percentiliitti has a monoclinic crystal system, with a unique characteristic of its internal crystal lattice. The presence of lithium and sodium within its structure plays a crucial role in the mineral's optical and physical properties.

In terms of physical properties, percentiliitti exhibits a glassy luster and is translucent to transparent. It has a brittle and somewhat fragile nature, prone to cleavage along specific crystal faces. The estimated hardness of percentiliitti falls within the range of 6 to 7 on the Mohs hardness scale, indicating its moderate to high durability.

In geological contexts, percentiliitti has been observed in highly alkali-rich pegmatites, often in conjunction with other lithium and boron-bearing minerals. Its relatively low density and a chemical makeup renders it somewhat unstable in the atmosphere, meaning it is unlikely to survive on the surface without protective measures. This factor contributes to the relative scarcity and unusual preservation conditions of certain percentiliitti specimens.