No, that isn’t a new yoga pose!  With a little bit of whimsy and imagination, this photomicrograph of a stone in glass looks like a frog swimming through green water. The cracked surface texture and tight solution sac are clues as to its origin, since both traits are characteristic of aluminosilicate refractory material. When this stone was analyzed via SEM-EDX, the interior consisted of recrystallized alumina and nepheline – both are commonly created by the reaction of an alumina-rich refractory with the glass melt.