To me, your bike sure looks like it has an aluminum frame.
Have you tried the magnet test?
Here's one like yours for sale in PDX.
Specialized Hard Rock Sport bicycle - 21-speed, 24" - bicycles - by owner - bike sale - craigslist
__________________
Carbon: Fuji SL2.1 Di2.......Aluminum: Cannondale Synapse 105........Steel: Vintage Specialized Sirrus
...