What is River Stone Quarts? Rivers tons s made from pure, natural quartz. About 93% of River Stone is mined crystals, one of nature's hardest surfaces. The only materials harder are diamonds, sapphires and topaz. The quartz is combined with high quality polyester resins and pigment to produce o natural stone without the maintenance. ‘What are the advantages of River§tone Quartz? Riverfront quartz surfaces do net requires sealing. conditioning or phishing. s lustrous finish will endure for years.