Yes, richer is a Scrabble word!

Adjective

1. Possessing material wealth

2. Having an abundant supply of desirable qualities or substances (especially natural resources)

3. Of great worth or quality

4. Marked by great fruitfulness

5. Strong; intense

6. Very productive

7. High in mineral content; having a high proportion of fuel to air

8. Suggestive of or characterized by great expense

9. Containing plenty of fat, or eggs, or sugar

10. Marked by richness and fullness of flavor

11. Pleasantly full and mellow

12. Affording an abundant supply