Hello natural knitters! I finished the Basalt Tank:
Please pardon the too-dark, unflattering photo. I knit this in Jo Sharp Soho Summer, a basic DK-weight cotton. My row gauge was pretty off from the pattern, so I ended up knitting a larger size which ended up fitting perfectly (after a run through my dryer).
I made a number of modifications. First, I knit half-hexagons on the sides, rather than whole ones, because I know I'd never wear the thing with whole hexagons. I doubled up the garter stitch border at the neckline for decency - if you look at the model in the book, that sweater is fairly low-cut on her. I also mirrored the garter border at the bottom for some additional length.
The major modification I did was to add waist shaping. I highly recommend waist shaping to anyone knitting this sweater - it is very, very easy to add, and makes the garment much more flattering. All I did was to cast on fewer stitches at the side hexagon pieces, and then I spaced the decreases evenly as I knit the hexagon. Simple and effective. I only wish that I had added more shaping!
More info (including my struggles with garter stitch) here.