[MISSABLE] This trophy is not as simple as it appears. There are a number of steps required to earn it:
1. Obtain the Ancient Nordic Pickaxe.
Talk to Glover Mallory, the blacksmith in Raven Rock. He will tell you to retrieve his Ancient Nordic Pickaxe, which is now in the possession of Crescius Caerellius. Find Caerellius (who will either be in the entrance to Raven Rock Mine or his house depending on whether you’ve completed “The Final Descent” or not) and convince him to return the pickaxe. Return to Mallory, who will allow you to keep the pickaxe.
2. Complete “The Fate of the Skaal” and ensure no villagers die.
This step is the most important of them all, as getting it wrong can lead to you being locked out of this trophy. Make sure you make a hard save once you learn the first word of the “Bend Will” Shout in the main quest. Then read the “Note on missable trophy” paragraph in this guide’s walkthrough. I will repeat again: make sure that Fanari Strong-Voice, Deor Woodcutter and Baldor Iron-Shaper all survive the fight with the Lurker when you cleanse the Wind Stone. If not, re-load your hard save and do it again. If you have made sure all three characters have survived, continue on to the next step.
3. “A New Source of Stalhrim”.
After Step 2, wait a couple of days and then travel to Skaal Village. Fanari Strong-Voice and Deor Woodcutter will be having an urgent conversation in the centre of the village, regarding the disappearance of Baldor Iron-Shaper. (Now you know why they had to survive - any of these characters dying beforehand would obviously not trigger this conversation). Speak to Deor to initiate the “A New Source of Stalhrim” quest.
To complete this quest, you must first follow Deor’s advice and travel to the Abandoned Lodge, north-east of Raven Rock. Kill the four Thalmor guards there and loot the Lodge Key from one of them. Go inside and downstairs, where you will find Baldor. He will tell you that you need to go to Northshore Landing to retrieve a map that was stolen from him by the Thalmor. Go to Northshore Landing and approach Ancarion, the leader of the Thalmor operation. You then have the option to persuade/intimidate him into giving you the map, killing him or pickpocketing it. Whichever you choose, head back to Skaal Village once you have the map and talk to Baldor to complete the quest.
4. Obtain Stalhrim.
The map that you retrieved in the previous quest will show a location in the north-west of Solstheim on your map called “Stalhrim Source”. Go there and mine some Stalhrim with your Ancient Nordic Pickaxe (the only pickaxe which will allow you to mine Stalhrim, hence the need to obtain it). Once you have a few pieces of Stalhrim, move to Step 5.
5. Craft a Stalhrim item.
Before you can make a Stalhrim item, you will need to have a smithing level of 80 and the perk which allows you to smith Ebony. If you have this, go to any forge (it doesn’t have to be Skaal Village) and craft any item of weaponry or armour in the “Stalhrim” tab, and you will finally unlock this trophy!
If you would rather use a video guide to help you with this trophy, then Guillermo has provided an excellent video which encompasses all of the above:
Be careful not to kill or let the Lurker kill any Skaal in the village when cleansing the stone there. If you do you will have to reload any earlier save. I have to create another character since I can't reload that far back. I tried using other glitch fixes but no luck. Please watch out for this one.
P.S. the reason being that if Deor Woodcutter dies he will not tell you about how the Skaal blacksmith went missing.
As a heads up, when I managed to keep everyone from dying after the lurker attack, someone said "Hey, everyone from the village is here." No such thing was said when anyone (important or otherwise) died, so if you get this saying, you know you saved everyone.
I was still able to complete this even with one of the dead. After you get the ancient Nordic pickaxe continue down into the mine and there will be a coffin in the wall covered in stalhrim you can mine.