[T-Mobile Samsung Galaxy Note 3] Apo11on:
I'll give you both, cat & mount outputs.

cat /proc/partitions:

u0_a230@hltetmo:/ $ cat /proc/partitions
major minor #blocks name
7 0 2111 loop0
179 0 30535680 mmcblk0
179 1 15360 mmcblk0p1
179 2 58816 mmcblk0p2
179 3 512 mmcblk0p3
179 4 32 mmcblk0p4
179 5 32 mmcblk0p5
179 6 2048 mmcblk0p6
179 7 512 mmcblk0p7
179 8 512 mmcblk0p8
179 9 10240 mmcblk0p9
179 10 10240 mmcblk0p10
179 11 14336 mmcblk0p11
179 12 3072 mmcblk0p12
179 13 3072 mmcblk0p13
179 14 11264 mmcblk0p14
179 15 13312 mmcblk0p15
179 16 13312 mmcblk0p16
179 17 7159 mmcblk0p17
179 18 3072 mmcblk0p18
179 19 1 mmcblk0p19
179 20 8 mmcblk0p20
179 21 8192 mmcblk0p21
179 22 9216 mmcblk0p22
179 23 2519040 mmcblk0p23
179 24 512000 mmcblk0p24
179 25 27316207 mmcblk0p25
179 32 512 mmcblk0rpmb
179 64 192251904 mmcblk1
179 65 1 mmcblk1p1
179 69 192241791 mmcblk1p5
254 0 2110 dm-0

mount:

u0_a230@hltetmo:/ $ mount
rootfs / rootfs ro,relatime 0 0
tmpfs /dev tmpfs rw,seclabel,nosuid,relatime,mode=755 0 0
devpts /dev/pts devpts rw,seclabel,relatime,mode=600 0 0
none /dev/cpuctl cgroup rw,relatime,cpu 0 0
proc /proc proc rw,relatime 0 0
sysfs /sys sysfs rw,seclabel,relatime 0 0
selinuxfs /sys/fs/selinux selinuxfs rw,relatime 0 0
debugfs /sys/kernel/debug debugfs rw,relatime 0 0
none /sys/fs/cgroup tmpfs rw,seclabel,relatime,mode=750,gid=1000 0 0
none /acct cgroup rw,relatime,cpuacct 0 0
tmpfs /mnt/secure tmpfs rw,seclabel,relatime,mode=700 0 0
tmpfs /mnt/secure/asec tmpfs rw,seclabel,relatime,mode=700 0 0
/dev/block/vold/179:69 /mnt/secure/asec vfat rw,dirsync,nosuid,nodev,noexec,noatime,nodiratime,uid=1023,gid=1023,fmask=0007,dmask=0007,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
tmpfs /mnt/asec tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/block/dm-0 /mnt/asec/com.probosoft.markethistorydelete-4 ext4 ro,dirsync,seclabel,nosuid,nodev,noatime,errors=continue 0 0
tmpfs /mnt/obb tmpfs rw,seclabel,relatime,mode=755,gid=1000 0 0
/dev/block/platform/msm_sdcc.1/by-name/system /system ext4 ro,seclabel,nosuid,nodev,relatime,errors=panic,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/userdata /data ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/cache /cache ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/persist /persist ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/efs /efs ext4 rw,seclabel,nosuid,nodev,noatime,discard,journal_checksum,journal_async_commit,noauto_da_alloc,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/persdata /persdata/absolute ext4 rw,seclabel,nosuid,nodev,relatime,data=ordered 0 0
/dev/block/platform/msm_sdcc.1/by-name/apnhlos /firmware vfat ro,context=u:object_r:firmware:s0,relatime,uid=1000,gid=1000,fmask=0337,dmask=0227,codepage=cp437,iocharset=iso8859-1,shortname=lower,errors=remount-ro 0 0
/dev/block/platform/msm_sdcc.1/by-name/modem /firmware-modem vfat ro,context=u:object_r:firmware:s0,relatime,uid=1000,gid=1000,fmask=0337,dmask=0227,codepage=cp437,iocharset=iso8859-1,shortname=lower,errors=remount-ro 0 0
/data/media /mnt/shell/emulated sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
tmpfs /storage/emulated tmpfs rw,seclabel,nosuid,nodev,relatime,mode=751,gid=1028 0 0
/dev/block/vold/179:69 /mnt/media_rw/extSdCard vfat rw,dirsync,nosuid,nodev,noexec,noatime,nodiratime,uid=1023,gid=1023,fmask=0007,dmask=0007,allow_utime=0020,codepage=cp437,iocharset=iso8859-1,shortname=mixed,utf8,errors=remount-ro 0 0
/mnt/media_rw/extSdCard /storage/extSdCard sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/data/media /storage/emulated/0 sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0
/data/media /storage/emulated/legacy sdcardfs rw,nosuid,nodev,relatime,uid=1023,gid=1023 0 0

---------- Post added at 04:54 PM ---------- Previous post was at 04:45 PM ----------

My own observations based on cat output:

Below are the 3 partitons in question. Based on the size, 179:64 and 179:69 both appear to be referencing the microSDXC, because there is no other memory inside my phone that large. 179:65 appears to be the partition TWRP is hung up on - the recovery thinks that's the external sdcard. The size is 1 byte, so it sees it as size 0Mb.

179 64 192251904 mmcblk1

179 65 1 mmcblk1p1

179 69 192241791 mmcblk1p5