The BitMEX .ZECXBT30M Index is a 30-minute TWAP of the Zcash price at Poloniex ending at 12:00 UTC from the .ZECXBT Index. These values are used for settlements. The TWAP is calculated using values from the BitMEX .ZECXBT index.
.ZECXBT30M Index Historical Values
This is the 30-minute time-weighted average price of BTC_ZEC on Poloniex, printed every 1 day.
The last 100 measurements are available here. More results can be retrieved from the API.