Makatite was found in cores of trona from three drill holes in the Evaporite Series of Lake Magadi, Kenya. The makatite occurs as white spherulites or radiating acicular aggregates that fill or partly fill cavities in coarsely crystalline trona. Makatite commonly makes up 5-20 percent of the core and locally replaces trona. Erionite, magadiite, anortho-clase, gaylussite, and organic material are associated with the makatite. Makatite is length slow, shows parallel extinction, and has the following indices of refraction: nmin. = 1.472, nmax = 1.487. Measured specific gravity is 2.072. Analysis on 1.2 grams of material from which trona had been removed by ultrasonic treatment in distilled water gave: SiO2 61.04, A12O3 0.15, Fe2O3 0.11, MgO 0.04, CaO 0.28, Na2O 14.76, K2O 0.09, H2O+ 12.71, H2O- 8.12, TiO2 0.14, sum 97.44 weight percent. The low total is probably due to an organic impurity. The composition can be expressed as Na2Si4O9·5H2O or as NaSi2O3(OH)3·H2O if H2O+ is arbitrarily assigned to (OH) groups and H2O- to (H2O). Differential thermal analysis shows sharp endothermic peaks at 80°, 100°, and 185°C; broad endothermic peaks at 530° and 810°C; and a broad exothermic peak at 675°C. The unit cell is crthorhombic, a = 16.840 ± 8 Å, b = 10.256 ± 4 Å, c=19.146+7 Å, V = 3,306.9± 1.5Å3. Strongest lines of the X-ray diffractometer powder pattern in Å are: 9.04 (53) (011), 8.41 (29) (200), 5.09 (100) (203), 4.217 (29) (303, 400), 3.419 (36) (030), 3.381 (29) (500), 3.127 (35) (231), 3.015 (21) (033), 2.996 (57) (116), 2.882 (42) (225). The name is from the Masai (Kenya) word, emakat, which means soda—in allusion to the high sodium content of the mineral.

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