. Bulletin - New York State Museum. Science. GUIDE TO THE MIXERALOGIC COLLECTION'S 75. Cassiterite (stream tin) Sn02 Cassiterite is the dioxid of tin containing $ oxygen and $ tin. Tetragonal crystals of the general type shown in fig. 192 are terminated with a low pyramid. Forms of prismatic habit with steeper and more complicated term- inations are also characteristic, and twins similar to the form shown in pi. 22x are quite common. Reniform masses and rounded pebbles with fibrous radiated structure (stream tin) are of common occurrence. The luster of cassiterite is adamantine and in
. Bulletin - New York State Museum. Science. GUIDE TO THE MIXERALOGIC COLLECTION'S 75. Cassiterite (stream tin) Sn02 Cassiterite is the dioxid of tin containing $ oxygen and $ tin. Tetragonal crystals of the general type shown in fig. 192 are terminated with a low pyramid. Forms of prismatic habit with steeper and more complicated term- inations are also characteristic, and twins similar to the form shown in pi. 22x are quite common. Reniform masses and rounded pebbles with fibrous radiated structure (stream tin) are of common occurrence. The luster of cassiterite is adamantine and in the case of crystallized varieties is usually splend- ent: the color is brown or black, sometimes red, grey or yellow, and the streak is brown. Cassiterite occurs in veins traversing granite, gneiss and other igneous and metamorphic rocks. It is found abundantly in Corn- wall and other parts of England, in Bohemia, Saxony, East Indies, Australia, Bolivia and Mexico; also in the United States in South Dakota, California and other states. Cassiterite is the sole source of tin. Rutile (nigrin) Ti02 Rutile is the dioxid of titanium and contains 4(K oxygen and 60$ titanium. In crystallization rutile closely resembles cassiterite (fig. 103). The crystals are prismatic in habit, often passing into acicular and hairlike forms which are vertically striated and are sometimes included in quartz and other minerals. Twinning, resulting in knee-jointed crystals and rosettes (pi. 222), is quite common. Rutile is occasionally found in compact masses which carry some iron. The luster of rutile is rather more brilliant and metallic than cassiter- ite and may be described as metallic-adamantine; in color it varies from brownish red to nearly black and when seen by transmit ted light in t ransparent varieties ii is deep red. Rutile occurs in granite, gneiss, syenite, mica, slate and some times in the limestones; it is frequently embedded in ether. Please note that these images are extracted from s
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