value of peelwood

Calculating approximate value of Peelwood deposit.....

Investing in the speculative mining industry is new to me, so I was wondering if someone could let me know if Im on the right track when trying to put an approximate value on the Peelwood deposit. I may be way off the mark in trying to work this out but below are my calculations.

Deposit at Peelwood (North + South combined as according to Sultan update on web site) http://www.sultan.net.au/assets/Uploads/0909SultanPeelwood-North-Mine-Update2.pdf on page 8.

Peelwood North deposit size = 895,000 tonnes

ZINC VALUE
895,000 x 3.94% = 35263 tonnes
Approx Zn spot price = AUD$2400/tonne
Value of Zn = $84,631,200.00

COPPER VALUE
895,000 x 0.8% = 7160 tonnes
Approx Cu spot price = AUD$8000/tonne
Value of Cu = $57,280,000.00

LEAD VALUE
895,000 x 0.73% = 6533.5 tonnes
Approx Pb spot price = AUD$2300/tonne
Value of Pb = $15,027,050.00

SILVER VALUE
895,000 x 0.000016% = 14.32 tonnes
Approx Ag spot price = AUD$18.40/troy oz
Approx Ag spot price = AUD$591,000/tonne
Value of Ag = $8,463,120

Therefore approx combined value of all metals = $165,401,370.00

SSC shares currently on issue = 888,537,435

Value per share = 19c per share

I understand this doesnt take into count costs involved in extracting the deposit and is based on today's spot metal prices.

Am I overlooking something or presuming something I shouldnt be? Any advice is welcome.