Mineralogy Database

Borax Bead Tests

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Borax Bead Tests

Table of Reactions Obtained with Borax

This table of flux fusion reactions with borax is based largely on the book "Determinative Mineralogy and Blowpipe Analysis" by Brush & Penfield, 1906. The reactions are observed by fusing a crushed (and roasted in the case of sulfides) sample of the mineral in a borax bead embedded on a loop of platinum wire. The color is observed in the bead after heating the sample with the oxidizing flame and then the reducing flame of the torch (blowpipe).

Oxidizing Flame Amount of Material Chemical Element(s) Reducing Flame
HOT COLD HOT COLD
Colorless Colorless Little or Much Si, Al, and Sn Colorless Colorless
Colorless Colorless or opaque White depending on the degree of saturation Little or Much Ca, Sr, Ba, Mg, Be, Zn, Y, La, Th, Zr, Ta, and Nb Colorless Colorless or opaque White depending on the degree of saturation
Pale Yellow Colorless or White Much Pb, Sb, and Cd Pale Yellow Colorless
Pale Yellow Colorless or White Much Bi Gray Gray
Pale Yellow Colorless or White Much Mo Brown Brown
Pale Yellow Colorless or White Medium W Yellow Yellow to Yellowish Brown
Pale Yellow Colorless or White Medium Ti Grayish Brownish Violet
Pale Yellow Nearly Colorless Little Fe and U Pale Green Nearly Colorless
Yellow Pale Yellow Little Ce Colorless Colorless
Yellow Yellowish Green Little Cr Green Green
Yellow Yellowish Green, almost Colorless Little V Dirty Green Fine Green
Deep Yellow to Orange-red Yellow Medium to Much Ce Colorless Colorless
Deep Yellow to Orange-red Yellow Medium to Much U Pale Green Pale Green to nearly Colorless
Deep Yellow to Orange-red Yellow Medium to Much Fe Bottle Green Pale Bottle Green
Deep Yellow to Orange-red Yellowish Green Medium to Much Cr Green Green
Green Blue Little to Medium Cu Colorless to Green Opaque Red with much Oxide
Green Yellow, Green, or Blue of various Shades Medium Various Mixtures of Fe, Cu, Ni, and Co (?)
See Below		 (?)
See Below
Blue Blue Little to Medium Co Blue Blue
Violet Reddish Brown Little to Medium Ni Opaque Gray Opaque Gray
Violet Reddish Violet Little Mn Colorless Colorless
Pale Rose Pale Rose Much Nd Pale Rose Pale Rose