DIAPHANEITY —LUSTRE— COLOR. 71 
Example, fibrous calcite, fibrous gypsum, and many fibrous 
minerals, more especially those which in other forms have a 
pearly lustre. 
6. Adamantine—the lustre of the diamond. When sub- 
metallic, it is termed metallic adamantine. ee some 
varieties of white lead ore or cerussite. 
b. The degrees of intensity are denominated as follows: 
1. Splendext—when the surface refiects light with great bril- 
liancy and gives well-defined images. Example, Elba “hematite, 
tin ore, some specimens of quartz and pyrite. 
2. Shining—when an image is produced, but not a well-de- 
fined image. Example, calcite, celestite. 
3. Glistening—when there is a general reflection from the 
_ surface, but no image. Example, tale. 
4, Ciiamer “ing—when the reflection is very imperfect, and 
apparently from points scattered over the surface. Kixample, 
flint, chalcedony. 
A mineral is said to be dull when there is a total absence of 
lustre. Example, chalk. 
3. CoLor. 
1. Kinds of Color.—In distinguishing minerals, both the ex 
ternal color and the color of a surface that has been rubbed o1 
scratched, are observed. The latter is called the streak, and the 
powder abraded, the streak-powder. 
The colors are either metallic or unmetallic. 
The metallic are named after some familiar metal, as copper- 
red, bronze-ve.low, brass-yellow, gold-yellow, steel-gr ay, lead- 
gray, lron-gray. 
The unmetallic colors used in characterizing minerals are 
various shades of white, gray, black, blue, green, yellow, ved aud 
brown. 
There are thus snow-white, reddish-white, greenish-white, 
milk-white, yellowish-white. 
Bluish-gray, smoke-gray, greenish-gray, pearl-gray, ash-gray. 
Velvet- black, greenish-black, bluish-black, grayish-black. 
Azure-blue, violet: blue, sky- ‘ine. indigo-blue. 
Emerald-green, olive-green, oil-green, g grass-green, apple-green, 
plackish-green, pistachio-green (yellowish). 
Sulphur-yellow, straw-yellow, wax-yellow, ochre-yellow, 
honey-yellow, orange-yellow. 
Scarlet-red, blood-red, flesh red, brick-red, hyacinth-red, rose- 
ved, cherry-red. 
