How to cite primary source first found in secondary source? I have the following situation (I am in the humanities):

I am writing a paper. In that paper, I several times cite a particular scholar's book. Now, in that book, this scholar cites (not quotes) a particular historical primary source.

As this looked interesting to me, I traced down this primary source (a diary entry), but I found it in a source collection different from that cited by the author. Moreover, when looking at the original source, I discovered that it contains additional content not summarized by that scholar that is useful for me. So I went ahead and directly quoted the primary source (including bits not mentioned by the author) in my paper.

Now, in the footnote, I am currently just providing a reference to the original source, not to the mentioned author where I first found a reference to that source. My question is whether this is okay?

According to the Chicago Manual (my citation style) and sources on the web, my understanding is that I only need to provide an additional comment in the form of "Source X, cited/quoted in ....." if I do not actually trace down the original source. So, it seems to me that what I am doing is fine. 

Still, as especially the advice on the internet is somewhat unclear and mostly jut designed to discourage citing of primary sources without having checked them, I thought I could also ask here.

Thanks!
If I'm understanding correctly, you are saying you read a secondary source, which led you to a primary source; then you cited material from the primary source that wasn't discussed in the secondary source; and your question is whether you need to cite the secondary source because it led you to the primary?

If so, I do not think you need to cite the secondary source. It feels polite to do so, sort of like using "via" on Twitter. But in an academic paper I do not think it is required.