Multimeric oxo‐hydroxo Al clusters function as models for common mineral structures and reactions. Cluster research, however, is often slowed by a lack of methods to prepare clusters in pure form and in large amounts. Herein, we report a facile synthesis of the little known cluster Al8(OH)14(H2O)18(SO4)5 (Al8) through a simple dissolution method. We confirm its structure by single‐crystal X‐ray diffraction and show by 27Al NMR spectroscopy, electrospray‐ionization mass spectrometry, and small‐ and wide‐angle X‐ray scattering that it also exists in solution. We speculate that Al8 may form in natural water systems through the dissolution of aluminum‐containing minerals in acidic sulfate solutions, such as those that could result from acid rain or mine drainage. Additionally, the dissolution method produces a discrete Al cluster on a scale suitable for studies and applications in materials science.