This is
a Quartz crystal from Brazil with Rutile inclusions. It is called
Rutilated Quartz.
This is a close up view
of the above rutilated Quartz.
A piece of massive Rutile.
CHEMISTRY TiO2
CRYSTALLOGRAPHY Tetragonal
CRYSTAL GROWTH AND HABITS Crystals of Rutile are commonly prismatic with striations parallel to their long axis. Twinning is common producing reticulated groups or as contact twins with 2, 6 or 8 crystal growths.
COLOR AND OTHER OPTICAL PROPERTIES Most commonly reddish brown, yellowish, bluish or violet; opaque to transparent (thin edges).
HARDNESS 6 - 6.5
SPECIFIC GRAVITY 4.2
LUSTER Adamantine to sub metallic
STREAK Pale yellowish brown
BREAKABILITY Good cleavage {110} and {100}, fracture is conchoidal to uneven; Brittle.
OCCURRENCE Rutile is a fairly common accessory mineral in high temperature - high pressure igneous rocks. It also forms in granitic pegmatites, gneisses, schists, marbles and is found as grains in sediments.
ASSOCIATED MINERALS Anatase, Brookite, Hematite, Ilmenite, Apatite, Adularia, Albite, Calcite, Quartz.
NAME From the Latin - rutilus for red.