Dataset:  ruins_church_age.csv

Source: M. Golez and A. Hladnik (2013). "Interpreting the Age of the Ruins of St. John the Baptist's
   Church with Multivariate Analysis," Journal of Cultural Heritage, Vol. 14, pp. 354-358.

Description: Principal Components and Cluster Analyses of 21 mortar samples (observations)
and 9 variables (features). Samples are also labelled by (R)oman, (G)othic, or (U)nknown.
Values less than Limits of quantification (LOQ) have been set at 0 (seems to have been done by authors).

Variable names (LOQ, when applicable)
ID
period
SiO2
Al2O3
Fe2O3    (LOQ=0.04)
MgO
CaO
Na2O
K2O      (LOQ=0.4)
TiO2     (LOQ=0.01)
LOI   (Limiting Oxygen Index)