TM, the so-called beryllium bells are really an alloy of copper that uses a very small amount (2% or less) of beryllium instead of the usual 25-35% zinc. This is done to make the copper "tougher". Why? Because the "relatively pure" copper is used to form the bells through electrical deposition of the copper in solution onto the surface of a mandrel which is subsequently removed and pure copper is VERY soft. This leaves a bell with exceptionally even wall thickness, no longitudinal seams, etc. The Beryllium apparently makes the "pure copper" a bit tougher but without impeding it's ability to be electrodeposited. I understand that the electroformed bells are now made by Anderson Plating for Schilke but this is only 2nd hand info. There have been stories about some rather special bells being made for some name players but someone else would have to post that info... I don't know where to find it. The beryllium content according to Marks is around 2%, the rest is copper. You will doubtless remember that Conn did the same thing with their "Coprion" bells (which stands for "copper-ion"). I'm not sure what trace element they might have used "back then"...perhaps an email to Margaret Downey would get a result. Also, while on the topic of beryllium...many folks claim that beryllium is deadly poisonous. Well so is almost every metal you can think of if it is powdered through machining processes and then inhaled! If I were in the market for this kind of bell material (and horn response) personally, I wouldn't give it a second thought. I did a check through "Mark's Handbook for Mechanical Engineers" and obtained some interesting info on different copper (brass?) alloys and their compositions and characteristics. If I could get into a certain other website I'd copy that info and post here...but I'll have to wait until the site becomes available again. Or else wait until I go back to work on Tuesday and repost from there. (Working a fund-raising Casino for our community band on Monday).