Actually, I was going to post on this very subject. On the 4th of July I ate nothing but chocolate chip cookie dough made from Butter Flavor Crisco. Disgusting, yes...but true. I was having very bad PMS, and preparing a large meal without any assistance. Well, I had no appetite for dinner, as you can probably guess why. I ate about 1/2 a hamburger without a bun. Within an hour, my gall bladder started acting up. No, I don't expect sympathy, I absolutely brought this on myself and I know that. At any rate, I was in the bathroom and had the familiar, pale clay colored stool and chaff (never having done a proper cleanse), and there was an ENORMOUS stone (1/2" in diameter) lodged on the outer portion of stool (I didn't get a stick or anything). There were smaller ones the next day all through the stool. I was shocked! How could this have happened? Just from having all that fat? I have to wonder.
BTW...olive oil CAN'T congeal at room temperature or above...that's why it's mostly polyunsaturated fat. Only saturated/animal fats "congeal" or solidify at room temperature. That's how you can tell the difference. So don't worry, it's not congealed olive oil.
Also, do a search for "beet" because one of the flushers on this forum did exactly what you mention: he dyed his flush so that he would be able to tell what was congealed and what wasn't.