Agaate

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Later

[Admin]

10/16
1. All four plots in Fig. 5 indicate a cessation of change occurring after about 60 Ma.
Given the moganite data plot, it is likely that total water in agates from hosts aged
between 60 and 180 Ma would show a similar percentage water content to that found
in hosts older than 180 Ma.
2. All four properties have demonstrated similar host age links. These properties show
that agates generally form around the same geological age as the host. There are
exceptions and the data shows that Brazilian and New Zealand agates have formed
long after the host formation.
3. Agates from Brazil and New Zealand are outliers in all plots. The mean predicted
formation age range of Brazilian and New Zealand agate using crystallite size, total
water, and moganite content is within 25 to 27 and 31 to 43 Ma respectively. The
density determinations have been excluded from these mean values; the predicted
ages of 39 and 21 Ma for the Brazilian and New Zealand agates are respectively so
much higher and lower than extrapolated data from the other three plots. The poor
density values are due to the small density spread of only around 0.05 gcm between
the highest and lowest values: any minor errors have a large effect on the outcome.
4. The density and crystallite size show age-related increases for the first 60 Ma; the
water and moganite content show age-related decreases. An important question, is
there any relationship between these increasing and decreasing changes?