Mineral in area around pit essentially turning scarlet (8)
I believe the answer is:
siderite
'mineral' is the definition.
(siderite is a kind of mineral)
'in area around pit essentially turning scarlet' is the wordplay.
'in' indicates putting letters inside.
'area around' becomes 'site' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'essentially' indicates the central letters.
'turning' says the letters should be written backwards.
'scarlet' becomes 'red' (synonyms).
The centre of 'pit' is 'i'.
'red' backwards is 'der'.
'i'+'der'='ider'
'site' going around 'ider' is 'SIDERITE'.
Can you help me to learn more?
(Another definition for siderite that I've seen is " Iron ore".)