Quartz is one of the most plentiful minerals on earth, making up about 12% of the earth's crust. But while quartz is common, it is far from boring -- the quartz world is remarkably diverse. Among the most fascinating phenomena in the quartz world are the unusual inclusions that are occasionally found in clear quartz crystals.
Gemologists use the term "sagenitic quartz" to refer to transparent colorless quartz containing needlelike crystals of rutile, actinolite, goethite, tourmaline or other minerals. The most well-known example is rutilated quartz, which contains inclusions of golden rutile or titanium.
Quartz with red inclusions of iron oxide is more rarely found, and is often sold under the name strawberry quartz or "red fire" quartz. Some specimens have very fine inclusions, only visible under magnification, lending the quartz a more or less uniformly strawberry color. Others have clearly visible inclusions and may appear as clear quartz with reddish needles, flakes or spangles.
Strawberry quartz gets its color from inclusions of various forms of iron oxide. There are four different but chemically related iron oxides that may be found in quartz. They include lepidocrocite (FeO(OH)), goethite (also FeO(OH) but with a different crystal structure), limonite (FeO(OH)*nH2O) and hematite (Fe2O3).
Some material sold as strawberry quartz is synthetic rather than natural; most of it is simply glass. Fruit Quartz is the general trade term for a group of colorful, translucent materials which are individually known by names such as "cherry quartz," "blueberry quartz," "strawberry quartz,"kiwi quartz," "pineapple quartz," and so on. They are commonly carved into jewelry components such as beads or pendants or into decorative objects. But don't confuse these synthetic products with genuine quartz with natural iron oxide inclusions.
Strawberry quartz is most often found in Russia and in neighboring regions such as Kazakhstan, as well as in Brazil.