Mineralization differs...

[Dan-Pa.]

Looks to me like F70 is preset at 90 and when you fastgrab ground balance after you bob several times the actual number will come up on the screen..Mine is usually early 70's and anyone know what is considered high or low mineralization as it seems 90 would be light but not sure...Info appreciated...

 

[Streak!]

the default GB setting on the F70. (the one it defaults to when you cycle the power) is close to Ferrite, and thats probably why it's the default number. I think the Average Ferrite value is closer to 85, but it probably runs a bit quieter at 90 if you just grab and use the machine without Gbing it.
If YOUR ground GBs at 70ish (like mine), its probably red clays, and is half decent soil. The type of mineralization will dictate what the numbers will be. I remember at a few sites in Va, when the soil was half decent, the F75 would Fast grab at 70 or so,,,,,but when you'd hit a particularly bad section, it would FG at closer to 90. (and you'd lose depth and ID would be worse). Keep in mind that the Gb or phase numbers will only tell you the type of mineralization, but the Fe304 meter will tell you the AMOUNT, and thats probably a better indicator of "Bad" ground. Streak!