Matty (Awvil),
Sorry, but I don't know of any sites. That means little, as I haven't looked for any. I've also picked up glass shards that have been "tumbled" in the surf zone, so I'm familiar with what you're looking to find out. I would guess that there are many variables involved...
An extremely interesting question. From only a practical point of view, I can tell you that glass is used in marine applications such as sea strainers, which are devices that filter incoming seawater for cooling purposes. Sea strainers have been used on boats for many years. I don't know...
