The eight most common elements in Earth's continental crust are:

1. Oxygen (O)

2. Silicon (Si)

3. Aluminum (Al)

4. Iron (Fe)

5. Calcium (Ca)

6. Sodium (Na)

7. Potassium (K)

8. Magnesium (Mg)

Therefore, any element not on this list is not one of the eight most common elements in Earth's continental crust.

To answer your question definitively, I need to know which element you are thinking of. Please tell me the element you're considering, and I can confirm if it's among the top eight.