Biotite Mica 1.5 Inch – 10 Mineral Specimens
by American Educational Products

  Biotite, a phyllosilicate mineral that is within the mica group, is generally though of as the dark mica of the series. It is a sheet silicate, and is composed of iron, magnesium, aluminium, silicon, oxygen, and hydrogen. These all form into a series of sheets that are bonded to one another by means of potassium ions, though the bond is relatively weak. It is sometimes referred to as iron mica, or black mica, due to its propensity to be iron-rich, and its black color.

  Found in both igneous and metamorphic rocks, and occasionally cleavable crystals like pegmatite, the largest documented specimen is approximately 7m2, or 75 square feet. It sees extensive use in potassium-argon and argon-argon dating of rocks, though it is usually only for determining the minimum age of a rock, due to argon’s ability to readily escape from biotite crystals at high temperatures.

Picture is representation of the specimens you will receive.
There may be smaller pieces in the bag from where the biotite has chipped, due to its fragility.

• Each bag of Biotite Mica contains 10 pieces.
• Each rock measures approximately 1 1/2 to 2 inches on the longest side.

Origin: Canada