Eventually, aluminum began to dissolve in the mercury forming a dull gray, liquid Al/Hg amalgam. The vial was capped and then agitated vigorously. Over the course of 10 minutes, the solution shifted to a dark peach-brown color, indicating reduction of the Cf 3+ to Cf 2+ . This solution was transferred to a 5 mL centrifuge tube and centrifuged to separate out solid Al(OH)3 generated by the amalgam. Meanwhile a second amalgam prepared in advance from 1 mL of Hg (measured with a volumetric pipette) and an excess of Al metal was stored inside of a 6 mL glass shell vial that was inserted inside a 20 mL glass scintillation vial. After centrifugation, the solution was pipetted over the Al/Hg amalgam inside the 6 mL shell vial. The outer 20 mL vial was filled to 75% capacity with a 1:1 solution of diethyl ether and pentane and capped for vapor diffusion. The solution was stored on a cold plate at 0 °C. Over the course of the next 4 hours, reddish-brown crystals of Cf(18crown-6)I2 formed, first around the Al/Hg amalgam where it contacted the glass of the shell vial, and then along the sides of the glass vial as well. Crystalline yield was approximately 50%.