Though other crystals should be highly stable. Quartz seems geologically and chemically stable, plain old glass ain't bad. Something reasonably cheap is probably preferable, both from the cost basis (an expensive-to-create archive is a challenge) and the repurposing challenge (a diamond-etched bibliographic archive might have other appeals to those who chance across it).
Even parchment proved sufficiently valuable that works were often repurposed (and lost) through palimpsests.
Though other crystals should be highly stable. Quartz seems geologically and chemically stable, plain old glass ain't bad. Something reasonably cheap is probably preferable, both from the cost basis (an expensive-to-create archive is a challenge) and the repurposing challenge (a diamond-etched bibliographic archive might have other appeals to those who chance across it).
Even parchment proved sufficiently valuable that works were often repurposed (and lost) through palimpsests.