Musical instruments and mutes can be made using several different metals. These different metals of course have different characteristics. Here I will discuss two aspects: what percentages of metals the alloys are made of and specific gravity ("weight"; not true, strictly speaking).

Alloys

Let's start with the alloys "brass" instruments are made of. There are many different types of "brass", and of course not everything on a "brass" instrument is actually made of brass.

A short list of the various alloys and their names.

Specific Gravity

Specific gravity is defined as "the weight of a body compared with the weight of an equal amount of pure water at 4°C (39.2°F)". Using this method, water will have a specific gravity of 1.0, lead will have a high specific gravity (11.39), cork a low specific gravity (0.24). It effects the perceived weight of the material.

First let's look at a short table, and then draw some conclusions from it.

As you can tell from the table, copper, zinc and the alloy brass are not all that far apart weight wise. Coprion is pure copper. Since copper is heavier than brass, you would expect an instrument with a coprion bell to be heavier than one with a brass bell. Also, less copper and more zinc makes the brass harder, and vice versa. Therefore, a coprion bell should in theory be softer than a brass bell.

Instruments can be lacquered, silver plated, gold plated or nickel plated as in the case of the 28A/38B Connstellation. As the table shows, nickel is about the same as the brass over which it is applied. Weight wise it probably behaves like an instrument with extra thick brass. Which can certainly add to the weight. Silver and gold are quite a bit heavier than brass. But unless I am seriously mistaken they are applied in a really thin layer, so your gold plated instrument doesn't suddenly weigh almost twice as much. Incidentally, it is my understanding that gold is usually plated over silver, and not directly over brass.

How about mutes? The table clearly shows why that great sounding and looking copper (bottom) mute is so awfully heavy: Copper is 3.375 times heavier than aluminum. That will certainly make a difference. Not listed are fibre and plastic. They aren't on the list I found on the internet, but I seem to remember another list somewhere which said they are lighter than aluminum.

And the pistons? On older instruments (which covers everything on this website) the pistons are stainless steel. "Stainless steel" isn't in the list I found on the internet, but considering the composition, I suspect it comes in at about 7.17. Which is somewhat lighter than the material most modern pistons are made from these days: monel (8.97).

Just a thought.