Brookite and Rutile in Quartz
This crystal is amazing. Brown platey crystals of brookite include this quartz crystal, with small needles of rutile growing off of the brookite. This is the conundrum of my mineral collection. Brookite and rutile share the same chemical formula, Titanium Dioxide, but are in different crystal systems and thus require different conditions to form. One of the basic rules of mineralogy I learned in class was that two minerals of the same chemical formula are not suppose to be found together at all, due to the fact they require different conditions and as conditions change, one will revert to the other or simply weather away. Yet this crystal holds both phases of this mineral in one sample, something that is supposed to be impossible! This inclusion facinates me to no end (can you tell?) This crystal measures about two inches tall.