Quartz is the most common mineral found on the surface of the earth. A significant component of many igneous, metamorphic and sedimentary rocks, this natural form of silicon dioxide is found in an impressive range of varieties and colours.
Inclusions of other minerals in rock crystal and smoky quartz are not particularly uncommon and are often highly attractive. To form rutilated quartz, earlier formed Rutile crystals were captured by later formed quartz as it grew thereby encasing the Rutile.
In some specific instances, such as asteriated quartz, rutile is thought to have been in solid solution in the quartz and, upon cooling, the rutile was forced out of the quartz structure, resulting in microscopic highly oriented needles. The light, playing off these oriented needles, presents a six-ray star typical of asterism ( a quartz version of star sapphire)
Rough black rutilated quartz