Also, for a grab bag of ~100 pieces from 1pF to 1000pF see auction # 183593057006.
Silver mica capacitors are high precision, stable and reliable capacitors. They are mostly used for Audio, Guitar Amps, Tube Amps, Hi-Fi and Radio applications at high frequencies where low losses (high Q) and low capacitor change over the time is desired. Circuit designers still turn to silver mica capacitors for high-power applications such as RF transmitters and electric instruments and amplifiers because cheaper ceramic and porcelain capacitors can't withstand heat as well. Silver mica remains widely used in high-voltage applications due to mica’s high breakdown voltage.