- Sunset Mine (washingtonminerals.com)
Index Batholith (Oligocene) - Uplift and erosion of the Old Cascade Volcanic Arc exposed plutonic rock of the Index Batholith near Index, Washington. Intrusive rock types found within the Index Batholith range in composition from granodiorite to tonalite.
- Decagon (Wikipedia)
In geometry, a decagon (from the Greek δέκα déka and γωνία gonía, “ten angles”) is a ten-sided polygon or 10-gon. The total sum of the interior angles of a simple decagon is 1440°.
