I hope you had a glass shield.!

I have a couple of the 13w version but neither seem to work .

We have a couple of the Philips TUV6 lamps, must get the pictures up soon.

That's a peculiar end shape of the discharge tube there. Is it made of fused silica or of a more traditional low-iron soft glass?

Not sure the glass type but it was quite a cheap lamp. It does look like the peculiar ends might actually be lamp seals. There doesn't appear to be the usual tubulation at the electrode.

If it's a cheap lamp, then it's more likely that a soft glass was used during production. Since you mention the electrodes, it seems that whoever made this lamp went for a flat tube sealing process, probably cheaper than having to make electrode stems. This means that they also likely used the same sealing method (without the electrodes) to close the other tube extremity, on the bridge side of the lamp... that would explain those two fused tips, they are just leftovers of exhaust tubulations.