Please use a scale, only a proper scale which shows mgs exactly can tell you this info, I'm gonna close this because someone could give you a reference with which you could od, their shards might be much thinner than yours plus a lot of other factorss, visual density doesn't equal weight in many cases, for example that pic has lots of shards, but I could have a single big shard that has the weight of 100mg, feel free to use a scale tho. there is no harm reduction in this either, quite the opposite. eyeballing is dangerous and I highly encourange avoiding it.