Minerals: Growth Interrupted Quartz
Locality: Minas Gerais, Brazil
Dimensions: 100mm x 36mm x 29mm
Weight: 128g
Provenance: ex. Mala Haslem Collection

Here is an exceptional example of growth interrupted quartz from Brazil, with remarkably clear interruption features running through much of the crystal and a beautifully developed stepped termination.

Growth interrupted quartz forms when another mineral grows against the quartz during development, leaving impressions across the crystal faces before that associated mineral is later removed or dissolved. The habit is most famously associated with Dalnegorsk in Russia, where some of the world's best known examples have been found.

This Brazilian specimen is unusually strong by comparison. The crystal is large, clear and highly lustrous, with repeated interruption marks extending across the column faces and continuing toward the termination. The stepped growth at the top is especially well developed, creating a layered structure while retaining excellent lustre throughout the crystal.

The interruption features are exceptionally easy to read across the surface, with sharp geometric impressions rather than only faint or isolated marks. Combined with the size, clarity and strong termination, this is one of the finest examples of this uncommon growth habit that I've personally encountered, and the strongest Brazilian example I've seen.