Hyalite Opal on Feldspar, with Schorl - NER 075 

Measurements:  47 x 33 x 27 mm 

Description:  Prolific aggregates of hyalite opal sit on a feldspar matrix which has several schorl crystals on it.

It fluoresces beautifully under ultraviolet light. One photograph was taken in natural daylight.

The specimen has a few nicks and contact marks.

Chemical Composition:  SiO₂•1.5(H₂O)  (opal)
                                       KAlSi₃O₈  (feldspar) 
                                       NaFe²⁺₃Al₆Si₆O₁₈(BO₃)₃(OH)₄  (schorl)  

Hardness on Mohs Scale:  (opal)  5.5-6 
                                         (feldspar)  6 - 6.5               
                                         (schorl )  7.5 

Location:  Erongo, Namibia.

Specimen Code:  NER 075