The Alaska citizen., 1916-08-21

mixed with the hubnerite Is large the mineral is also called wolfra mite.
 COLOR OF HUsNsRITE. Hubnerite ranges in color from reddish brown to hair brown black ish-brown and occasionally bluist black The powder formed by crush ing or sCraping the mineral ranges in color from light grayish-browr to hair-brown and almost chocolate When the quantity of ferberte pres ent is large the colors of the min eral and it's powder become dark CT. often nearly black. The streak made with the mineral on an un glazed porcelain surface is of much the same color as the powder. but may incline to greenish gray The lustre of fresh surfaces of the min eral ranges from bright. somewhat metallic to rather dull. Thin sli vers or plates of the lighter colored hubnerites let a little light through but are not transparent. The darker ones are opaque.
 The commonest crystal forms are large and blade-like. but tabular and chisel shaped forms with small ridges and grooves are quite com mon. The crystals split easily in certain directions leaving smooth flat surfaces which are often very shiny These cleavage surfaces are often spotted with lighter colored patch es. The bladed crystals often stick out into the quartz or rock in which they are bedded. This is not seen with ferberite and rarely with vol. frantic
 The mineral is brittle and easily powdered, and can De scratched by hard knife blade
 It is very heavy when free from quartz and rock matter, weighing three times as much as a piece of quartz or common rock of the same piece of iron ore of the same size. It is not attracted by magnet but it sometsnes is associated with magnetic
 CoLoRS OF FERBERlTE.
 Ferberite ranges in color from dark steel gray to black and bluish black The powder formed by crush ing or scraping the mineral is dark chocolate brown to black As the quantity of hubnerite present in creases the color of the mineral, the mineral powder and the streal. becomes lighter The streak is gen appears almost black The lustre of fresh surfaces is commonly bright, frequently resembling a metal surface. In open spaces it often crusts the surface with very small black chisel shaped crystals hay ing very bright surfaces. Occa- sionally the. crystals show peacock colors. A variety known as "steel tungsten" or "steel ferberite" has steel gray color and metallic lus- tre on fresh surfaces The tex ture of ferberlte is very fine, and it seldom breaks away in flakes, as does specular hematite. IL often occurs scattered in very fine grains through the "hornstone," giving it gray to black color. It is three times as heavy, volume for volume, as quartz.
 Wolframite is Intermediate in col or and streak between hubnerite crystal habit as ferberite, but rarely occurs in the long blade-like crys- tals so common in hubnerite.
 Scheelite resembles quartz, but is more than twice as heavy, volume for volume, It is not so glaSsy looking as fresh quartz. and ire quently shows flat cleavage faces, while quartz generally shows curved and irregular fracture surfaces. It an be scratched with knife, but quartz Is harder than the knife blade It sometimes occurs in crys- tals of pyramid shape. It is trans parent when pure and not fractured too badly.
 TESTS FOR TUNGSTEN
 Tests for Tungsten-The simplest chemical test is made by powder ing the mineral very fine and boil ing it for ten to fifteen minutes in strong hydrochloric acid. If it is d tungsten mineral a yellow powder will be formed and will settle to the bottom when the boiling stops If a grain of metallic zinc or me tallic tin is added to the solution and it is again boiled blue color will appear. Longer boiling will turn the solution brown.
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