Trimming

The one preparation step that cannot be undone the next morning.

Irreversible, so think first

Everything else is recoverable. A trim is not, and an over-trimmed specimen is visible as one for ever.

Live with a specimen for a week before trimming it. The urge to trim is strongest on the day you found it, which is exactly when your judgment about it is worst.

Why to trim

To bring a specimen into a size class, which is normal and expected.

To remove matrix that contributes nothing and only adds weight.

To give the specimen a stable base so it sits as it should be seen.

To remove damaged matrix that distracts from the crystal.

Not to make it fit a box you already own, which is the reason that produces regret.

How

A hydraulic trimmer if you have access to one: controlled, predictable, and it makes a clean break along a line you chose.

Hammer and chisel otherwise, working from the back, small bites, supporting the specimen fully so the shock does not travel into the crystals.

Score a line first and work along it rather than taking one decisive blow.

Protect the crystals physically while you work, padding over them, because the chip that lands on a termination comes from the piece you just removed.

When not to

When the matrix carries information: an association, a contact, a texture that places the specimen.

When you are unsure. The specimen will still be trimmable next month.

When somebody who knows the locality has not seen it. Classic-locality material has conventions about how it is presented, and a trim that violates them costs money.

And never before cataloguing, because a trimmed specimen and its pre-trim photograph are both part of the record.

References