Pureblood Weasleys?

[Shannon]

No: HPFGUIDX 110405

A friend of mine and I are discussing various possibilities regarding 
who the half blood prince might be.  She asked me if the Weasleys were 
pure blood, and I said that they were. But when we started talking about 
it, I can't remember any moment in the books in which this is outright 
stated.  At first I thought, well, they're on the Black family tree and 
they wouldn't be if they weren't pure blood. But on checking, I saw that 
they were not, in fact, on the tree.  Sirius says he's related to Molly 
by marraige, and Arthur is a second cousin once removed. But they aren't 
actually on the tapestry.  He says, "If ever a family was a bunch of 
blood traitors it's the Weasleys." (OOP pg 113 US edition).    Ron, in 
COS, says "Most wizards these days are half-blood anyway. If we hadn't 
married Muggles we'd've died out."  (pg 116, US edition).  Which does 
seem to imply that marrying Muggles (which wasn't even what they were 
talking about, they were talking about Mudbloods...wizarding children 
from Muggle parents) is familiar and normal to him.  He also says on the 
same page, "There are some wizards--like Malfoy's family--who think 
they're better than everyone else because they're what people call 
pure-blood."   He says "they're" which might suggest he's speaking of 
something other than himself....he could just as easily have said 
"...who think pure-bloods are better than everyone else." 

I do remember Ron telling Harry that all his family were wizards, but 
that doesn't necessarily mean *everyone,* it could just mean current family.

I checked the lexicon and it says they are pure blood, but again is this 
just assumed or is there a direct quote or something from the book that 
confirms it?  Because I honestly can't think of where it might have been 
explicitly stated.

Shannon, the eternally confuzzled.