It's actually a material called Bakelite, an early plastic made using a reaction of formaldehyde phenol resin under heat that was used extensively in the earlier part of the 20th century. An internet search for 'Bakelite' will explain it's history and many uses.
'I do not think we can hope for any better thing now.
We shall stick it out to the end, but we are getting weaker of course, and the end cannot be far.
It seems a pity, but I do not think I can write more. R. SCOTT.
Last Entry - For God's sake look after our people.'
In memory of Capt. Robert Falcon Scott, Edward Wilson, Henry Bowers, Lawrence Oates and Edgar Evans. South Pole Expedition, 30th March 1912.
Oh i got it, many thanks for your information Ned!