Heading north out of Gagnon, the road is paved again. Nicely paved, actually, with a fairly decent surface. This section of paved highway goes on for a long way (about 90 kilometres), until about kilometer 480, near the old mine site of Fire Lake.
At fire lake (km 480-ish), the highway turns back to gravel. The highway then heads north in a more twisty fashion, and is always near a railway that services the Mont Wright minesite. The quality of the gravel is poorer - more coarse and looser. As a result, you will be going slower along this section and being more vigilant about flying rocks from other vehicles. This next section of gravel road -- from here to Mont Wright -- is about 60 kilometres in total length.
At about the 520km mark, you will see a strangely-colored flat-topped mountain in the distance. This is your first sight of the huge iron ore mining operation at Mont Wright. The highway makes a few twists and turns as it heads in the direction of the mine, and soon you will drive right by the mine's tailing hills and drive fairly close by the center of the mining operations (at about kilometer 540).
At Mont Wright, the highway turns back to pavement, then continues east a few kilometres to the turnoff with the mining town of Fermont (km 560). Gas and other services are available at the town of Fermont. A few kilometers after Fermont, you reach the Labrador Border (at km 565), and the start of the Trans-Labrador Highway.
(if you'd like to read my in-depth highway description of the Trans-Labrador Highway, click here