Does > help Google to see content as a citation and not a duplicate?

[esiow2013]

Thanks in advance!

[JaneCopland]

As Marie says, doing this isn't likely to throw a penalty your way due to the way Google handles duplication (and you're unlikely to be doing this on page after page after page of your website). You always want to link to the source of the quote, with the (very likely) assumption that the source is not linking back to you (and if they are via a trackback "comment", that link is probably nofollowed).

If you're quoting something like the author is in this example, you've taken quite a hefty chunk of text from the source, but you're providing a LOT of original commentary, linking back and providing a blockquote tag (which is not "necessary" but probably sends a good signal).

[AlanMosley]

Spot on, unless your site is trying to spam results with DC, you don't have a problem,

And yes it would help google understand what you are doing.

[MarieHaynes]

John Mueller from Google has said repeatedly that there actually is no duplicate content penalty.  If you have content that is similar to another site then Google will decide who the originator is and show that site on search results.

If you've take a quote from somewhere, that's fine.  It doesn't matter whether you use it in "blockquote" tags.  However, if the vast majority of your site is made up of other people's quotes then this likely can affect your site in the Panda algorithm.

[TheeDigital]

I would hope that you have enough unique content on the page for it not to be considered duplicate, but yes this is a best practice.  Other items that might help would be just take as much of the quote as you need, as in don't blockquote a whole wiki article, add your own original content as well, and don't forget to link back as well.