Morphometric data on topotype assemblage of <Emphasis Type="Italic">Miogypsina (Lepidosemicyclina) droogeri</Emphasis>, foraminifera from Kachchh,Gujarat

For the first time we report alluaudite from India, which is metamict and is hosted in a zoned pegmatite, near Pisangan, Ajmer district, Rajasthan. Alluaudites known till date, all over the world, are non-metamict type. Therefore, the alluaudite reported from the area is the first locality in the world for the metamict-type of alluaudite. The most conspicuous features exhibited by the alluaudite are various types of cracks in different directions and shapes, including its isotropic nature. The calculated crystallographic parameters of the reported alluaudite are: a₀ = 11.9874 Å, b₀ = 12.5144 Å, and c₀ = 6.4136 Å, β = 114.240 with unit-cell volume (V) = 877.31 ų, which are in agreement with the values of alluaudite standard. Geochemical data indicates high content of P (32.30% P₂O₅), Fe (30.2% Fe₂O₃), Mn (10.62% MnO), besides Mg (7.71% MgO), Ca (5.60% CaO), Na (3.40% Na₂O) and Si (2.30% SiO₂), and appreciable amount of water of hydration (3.50% LOI). It is highly radioactive due to uranium (2.28% U₃O₈) and thorium (185 ppm Th). Calculated structural formula of the alluaudite is Na¹⁺_0.59Ca²⁺_0.54Mn²⁺_0.80Mg²⁺_1.02Fe³⁺_2.03Al³⁺_0.037U⁴⁺_0.043P⁵⁺_2.45O₁₂. The chondrite-normalised plot shows enrichment of HREE relative to LREE with pronounced negative Eu-anomaly (Eu/Eu* = 0.46). Such a high negative Eu-anomaly suggests extremely fractionated nature of the host pegmatite.