A phase diagram often used to illustrate phase change metamorphism depicts relationships between three minerals made up of these two elements and oxygen, namely andalusite, kyanite, and sillimanite. These are the two heaviest elements that partly make up kaolinite. Metal ions create holes in a network of bonds between oxygen and these two elements in zeolites. The Conrad discontinuity has been posited as the lower limit of a region whose composition has a name combining these two elements' symbols, which takes up much of the upper asthenosphere. By definition these two elements, as well as oxygen, must be present in any feldspar molecule. After oxygen, these two elements are the most abundant elements in Earth's crust. For 10 points, name these two elements, respectively a metal often used for drinks cans and a common semiconductor. ■END■
ANSWER: aluminum and silicon [or aluminium and silicon; or Al and Si; accept pairs of answers in either order; prompt on sial]
<Joseph Krol , Science - Earth - solids>
= Average correct buzz position