Kenyaite
Chemical formula: Na<sub>2</sub>Si<sub>22</sub>O<sub>41</sub>(OH)<sub>8</sub>·6H<sub>2</sub>O
Kenyait is a hydrated sodium silicate, forming characteristic white, fibrous or earthy aggregates in alkaline saline lake sediments.
Description
## Characteristics Kenyait is a mineral from the silicate group, chemically a hydrated sodium silicate. It most often occurs as thin layers, rosettes, or spherulitic aggregates with a fibrous structure. Its appearance is usually dull and earthy, resembling chalk or gypsum. Individual crystals are in the form of microscopic laths and are rarely visible to the naked eye. Aggregates are very light and brittle. ## Physical properties This mineral is relatively soft, with a hardness of about 4 on the Mohs scale. It is characterized by a very low density, approximately 1.96 g/cm³, which makes specimens extremely light. The luster on fracture surfaces can be pearly, but most often it is dull or earthy. It is translucent to opaque. ## Colors and varieties Kenyait is usually white, less often colorless. It does not form colored varieties nor does it have commercial names for its forms. ## History and name The mineral's name comes from Kenya, where it was first identified. It was described in 1967 by Hans P. Eugster, who discovered it in sediments from Lake Magadi. It is a typical mineral for the specific, highly alkaline environment of this lake. ## Applications Kenyait has no industrial applications. Its significance is purely scientific, as an indicator of specific geochemical conditions, and as a collector's item, being a rare mineral characteristic of unusual environments.
Diagnostic features
## Identification Characteristic features of kenyait include its low density (it is very light), white color, earthy or chalk-like appearance, and occurrence in the form of fibrous rosettes and layers. A key indicator is its environment of occurrence - alkaline saline lake sediments. ## Distinguishing from similar minerals Kenyait is almost identical to magadiite, with which it often co-occurs and is often confused. Reliable differentiation of these two minerals usually requires X-ray diffraction (XRD) analysis. From other white, earthy minerals, such as calcite (chalk) or gypsum, it is distinguished by the lack of reaction with hydrochloric acid and significantly lower density. Unlike trona, which also occurs in similar environments, kenyait does not form large, vitreous crystals. ## Crystal forms Kenyait forms microscopic lath-shaped crystals that aggregate into larger forms. It is most often observed as spherulitic rosettes, fibrous aggregates, or thin, compressed layers in sediments.
Geological environment
## Genesis Kenyait is a mineral of sedimentary origin. It forms by precipitation from silica- and sodium-rich waters under extremely high alkalinity (high pH) conditions. It is a typical evaporite mineral formed in alkaline soda lakes. ## Mineral associations This mineral often co-occurs with other rare evaporite minerals, such as magadiite (with which it is closely related), trona, halite, williaumite, nahcolite, and with forms of quartz (chert, Magadi-type chert). ## Localities The most important and classic locality is its discovery site - Lake Magadi in Kenya. It also occurs in other similar environments worldwide, including in the sediments of Lake Natron in Tanzania, in the Green River Formation in Wyoming (USA), and in the Mont Saint-Hilaire alkaline complex in Quebec (Canada).
Rarity
Not very common
Collector aspects
## Quality criteria The most valued by collectors are specimens with well-formed, large rosettes or spherulites with a distinct structure. The purity of the specimen is important - the fewer impurities and rock material, the better. Samples from the type locality (Lake Magadi) and specimens where kenyait occurs in association with other rare alkaline minerals, such as williaumite, are of particular value. ## Popular localities By far the most known and desired source of kenyait for collectors is Lake Magadi in Kenya. Specimens from this locality are considered classic for this mineral.
Care and storage
## Cleaning Kenyait specimens should only be dry cleaned, using a soft brush to remove dust. Any contact with water and other liquids should be avoided, as the mineral is hydrated and can be damaged. ## What to avoid Contact with water, acids, and other chemicals must be strictly avoided. The mineral is sensitive to changes in temperature and humidity, which can lead to its dehydration and disintegration. It is very soft and brittle, so it should be protected from impacts, scratching, and pressure. ## Storage It is recommended to store specimens in closed, padded boxes to protect them from mechanical damage and dust. It should be stored in a dry place with stable temperature, away from direct sunlight.