/lib/udev/rules.s/99-observatory.rules: 


# Gemini Mount

SUBSYSTEMS=="usb", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6001", ATTRS{serial}=="FTCC5RMS", MODE="0666", SYMLINK+="mount"


dmesg says: 

[  142.297414] usb 1-1.3.3: new full-speed USB device number 8 using dwc_otg
[  142.435477] usb 1-1.3.3: New USB device found, idVendor=0403, idProduct=6001
[  142.435496] usb 1-1.3.3: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[  142.435509] usb 1-1.3.3: Product: USBSERIACONRVERTER
[  142.435521] usb 1-1.3.3: Manufacturer: FIDI
[  142.435533] usb 1-1.3.3: SerialNumber: FTCC5RMS
[  142.443847] ftdi_sio 1-1.3.3:1.0: FTDI USB Serial Device converter detected
[  142.444007] usb 1-1.3.3: Detected FT232BM
[  142.444920] usb 1-1.3.3: FTDI USB Serial Device converter now attached to ttyUSB0

So not connected to /dev/mount...