What is this stuff on my upper radiator hose?

[showme]

Had a leak at the engine end of the upper radiator hose due to a clamp that had cracked in half on the underside, where it was out of sight. After I pulled the hose, I found this stuff in it. When I started to clean off the fitting it attaches to, I found a scale of the stuff about 1/16" deep all the way around, with it being thicker on the bottom side. Since we have so much lime in the water here in southeast Missouri, I'm guessing that's what it is, but the amount that was in the hose was a sandy texture, which isn't how lime normally accumulates. I'm wondering if someone put some additive in or something. It's not a big deal (I don't think), but I'm curious to see what everybody else thinks since I've never come across this before. Probably just a build up of lime from the leak, but I don't know. Thanks, Lee

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[VStar650CL]

Looks almost like 20 year old pipe dope, lol. Is the metal underneath the scale smooth, or lumpy and pitted? Aluminum alloys almost all produce some sort of whitish scale when they corrode.