In early 2000 silestone made a big branding push that you can see did not have the staying power. It looks like consumers moved to granite very quickly since 2007.
I think the reason that quartz countertops are starting to see more search volume is that the market is becoming flooded with imitation quartz countertops at very inexpensive prices.
These materials do not have the same properties of the leading US brands and the consumer is really paying the price because they don't know how to tell the difference.
check out this link for countertop search trends
Granite vs quartz vs silest…