Purification of isoborneol
iso-Borneol is a fairly common reagent, and methods for its preparation and purification are readily accessible (even without journal access). For information, the entry in Purification of Laboratory Chemicals suggests recrystallising from ethanol or petroleum ether, melting point data is also provided as a way of assaying the resulting material  (though NMR would be better). 


  dl-Isoborneol [124-76-5] M 154.3, m 212° (sealed tube). Crystallise isoborneol from EtOH or petroleum ether (b 60-80°). It sublimes in a vacuum. The 4-nitrobenzoyl derivative has m 153°. [Yager and Morgan J Am Chem Soc 57 2081 1935, Beilstein 6 II 80, 6 III 299, 6 IV 281.]
  
  Taken from Purification of Laboratory Chemicals, 7 ed. Armagero and Perrin


Its worth noting that a powder and flakes are essentially just two amorphous forms, and there isn't really any benefit of having one over the other (if anything, the powder is more convenient to handle).