Do you hae a map of the best geo sites to check as I will have to try a few. Also why not bio sites polporus growths? they drop selenium?Note that geological signal sites generally are much more spread out than the crystalline shard sites. You should be driving around the site looking for crystalline fragments as these will drop selenium 2/3 of the time. The sites are also pretty big in comparison to the shard sites. You may of course also look for any other materials that you are low on from other drops, but if you were already at the shard sites you will probably already be full on those.