This specification covers the electrical, visual, and physical properties of natural blocks and films made from mica that are suitable for use in fixed mica-dielectric capacitors. The materials under this specification are of three forms and four classes. Samples should be taken and tested according to the test methods prescribed here. All samples should adhere to the specified values of conducting path, Q value, dielectric constant, weight loss on heating, thickness uniformity, temperature coefficient of capacitance and retrace, and amount of air inclusions, waves, cracks, tears, pin holes, stones, buckles, and ridges.