A hydrous silicate of potassium, magnesium, and aluminum, phlogopite often exhibits an unusual copperlike or bronze-red color, though it may also be yellowish or greenish hued. The precise coloration of the substance primarily depends upon its iron content, which also affects the density of the mineral. Phlogopite is usually formed metamorphically, but may also develop from plutonic forces. Significant deposits of the mica, which often appears as brown flecks in crystalline dolomite and marble, can be found within the United States in New York and New Jersey, as well as in various other parts of the world, such as Finland and Canada.