Drat. I think I threw away the ball band. It's 4-ply, feels like wool, and would be the right thickness for sock yarn. Oh well. I only have one ball of it, so I'm playing around with crocheting a little scarf.
Here's what the yarn looks like:
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Update: Aha! It's Ornaghi Filati Luna Park 202:
Content: 100% superwash merino wool
Made in: Italy
Size: 50g/200m - 1.75 oz/210 yards
Gauge: 33 sts/4" using needles #3-4US, for sock you might want to use #1-2US.
Care: machine wash gentle/dry flat
Ravelry link:
the yarn.