The phrase "a thing of which" is correct and usable in written English.
It can be used when referring to a specific object or concept in a formal or literary context, often to emphasize the relationship between the thing and its attributes or qualities.
Example: "This is a thing of which many have spoken, yet few truly understand."
Alternatives: "an item that" or "a matter of which".
A rather formal Englishman, a friend of ours who is giving some lectures at Harvard, took several of his shirts and stiff collars to a laundry in Cambridge the other day and was waited on by a teen-age girl whose high standard of courtesy is a thing of which her fellow-countrymen can all be proud.
…but even if I am, I think it's fair to say that this is a thing of which many people are frightened.
What will not be true, however, is that whatever the predicate "is a surman" is true of, as it occurs in the language-fragment reinterpreted in Quine's way, is a thing of which "is a man", as it occurs in English as a whole, is true of.
The Monsal viaduct - which once carried the railway line between Manchester and London - is now accepted as a thing of beauty which adds to the valley's wonder.
But Mr. Leavitt and his allies keep making a big thing of which presidential candidate Mr. Orton will support on Nov. 7.
Aristotle's explanation is that the same things cannot always be said of both a predicate and the thing of which it is predicated in other words, predication is not transitive.
Ironically, the market for sexy "bad girls" smoking weed on camera only grows as weed becomes a more acceptable, less "bad" thing of which to partake.
They consider that growing cocoa trees under shade is a thing of the past, which their experience caused them to abandon.
The play also unequivocally shows how a persecuted old woman becomes the thing of which she is accused.
There have been rumors floating around about what is inside the Governor's bill, a few things of which I am not too happy about.
Since the 2010 target was adopted, we in the EU have accomplished a number of things of which we can be proud.
