Congratulations on your first delft casting!

It's just a miscast, sounds like the first bit of metal cooled before it got into the mould, get your gate as large as you can get away with so metal gets to the bottom of your casing as soon as possible.

Get as little distance between the crucible and the casting as you can, pouring in one smooth, fluid motion (I've read it described as pouring milk into coffee) and not fannying around between lifting to pour and tipping.

It can be a bit tricky, especially with only a few grams of metal, to keep everything as fluid as possible between melting and pouring. It takes practise but every miscast has something to tell you about how to get things (eventually!) right.

There are no wasted castings as long as you look for what it has to teach you.

It's all cool in the gang