Magnesium citrate (3:2) (3 magnesium atoms per 2 citrate molecules), also called trimagnesium dicitrate, trimagnesium citrate, or the ambiguous name magnesium citrate. The substance may come as anhydrous or hydrated salt with varying properties.
The anhydrous salt has good solubility in water (~10% or more at 25 °C) and contains 16.2% elemental magnesium by weight. Its taste is slightly bitter-alkaline.
The hydrated salt may have 3 to 14 molecules of water attached to it and has much lower solubility in water (2% or less at 25 °C). This form doesn't have any noticeable taste.
References