• Montgomeryite
  • Montgomeryite
  • Montgomeryite
  • Montgomeryite
Rare Minerals


ID: CC18513
An excellent specimen of the very seldom encountered species Montgomeryite, a calcium-magnesium-aluminium phosphate hydroxide and named for the American mineralogist Arthur Montgomery.  From the Tip Top mine at Fourmile in Custer County, South Dakota, USA, the salmon-pink to burnt-salmon-pink Montgomeryite crystals occur as acicular sprays of up to 5 mm in diameter and 0.5 to 1 mm tall. A 2.5 x 2.0 cm area is also densely coated with lustrous black micro-crystals of what is likely Robertsite, but this is not confirmed.  Tip Top mine is the type locality for Robertsite and this is often found here in association with Montgomeryite.  An excellent example of Montgomeryite from the famous Tip Top mine.

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7.3 × 5.8 × 2.8 cm
Oxides and Hydroxides, Phosphates, Arsenates and Vanadates, Rare Minerals
Tip Top Mine, Custer Co., South Dakota, USA, North America

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