taultunleashed

Ive done extensive exploring of all 3 continents in search of the best mining / quarrying spots. For Tin and Slate, Between (to the north of) refugee camp and the tautinum docks, and to the north east, make a circle out of it, I would start by going north sort of along the coast then up eastwards up the mountains, there is a ton of tin / slate here, more then 20 nodes of each, in a 15 min walk cycle I got to 220 Mining / quarrying in 45 mins or so. (from 110)

EDIT The above post refers to Qualia, Pretty much straight south of Khal, You should see the refugee camp on your map, Its a little SE of the undead ruins on the east side of the west river.

For Iron / Sandstone goto the Elephant graveyard (Qualia), ive counted 11 nodes of iron, 2 of tin, 14 of sandstone and a few slates. Thats a lot of iron nodes, there are only 2 other places ive really found any, thats in the lvl 20 forest on kojan (there are a few iron deposits, hard to get to though) And on the furthest NE island in Qualia, thats a good spot to mine it, and you wont have to contend with mobs. (basically an empty island except for 1 lizard spawn.

Not knowing the geography well, I cannot make out where you are describing in the first paragraph.

Where's the elephant grave?

For iron/sandstone, best spot I've found was around the Infileum mines. You should know it, it's where you do the cloak quests after 20+.

North east of that mine, is a pit with lots of spiders. Like 20+ nodes in that tiny little pit. I got from 240 mining to 300 in a day. TONs of iron. If there's other people clearing spiders for quests, it will be even easier to just run around and mine.