Edit: From the UK site, there is good reason to believe that Twining's is ALSO Iron Goddess of Mercy, but it tastes nothing like the IGoM I got from Numi. From what I've read about oolong, "nutty and fruity" are not typical characteristics of IGoM, where as the floral, honey suckle-like flavor of Numi's is. So I'm thinking Twingings is mislabeling their tea since Iron Goddess of Mercy is a well known type of oolong. It wouldn't be the first time I've seen tea mislabeled so its not unthinkable. This chances the question, to "what oolong is nutty and fruity".
Recently I discovered that I love Twining's oolong tea. It has a light, refreshing flavor. Unfortunately, in the US, it is only sold in units of 20 bags, so I purchased a 1 pound bag of Numi's Iron Goddess of Mercy.
The tea is certainly good, but I prefer the Twinings. Where Twinings is nutty and fruity, and it tastes like neither black nor green tea, Numi's tastes much like green tea with a floral falvor. Its still good, but I like the Twinings better.
I then looked up oolong and found that unlike green, black, and white tea, oolong has a wider range of variation. While its true you can have different types of green or black tea (Darjeeling, gunpowder green, sencha, macha...) those all have, at their base, the same ingredient: camellia sinensis leaves that have been dried and processed either with 100% oxidation (black), or 0% (green and white). The difference between green and white is then when the leaves are plucked.
In the case of oolong, the oxidation, and the means of oxidizing, varies greatly (from 8% to 80%), and from mild bruising to fermenting. Iron Goddess of Mercy is one such type of oolong.
My question is then, "what type of oolong does Twinings sell" because I would like to buy a big bag of the stuff (albeit from another company).
Another bit of information that might help: The tea, brewed, is darker than the Iron Goddess of Mercy tea (at least Numi's) which implies greater oxidation.