Vermiculite from Philadelphia County, Pennsylvania, USA
USA | |
| Gordon, Mineralogy of Pennsyvania, 1922 - p. 224 |
| Gordon: Min. Penn (1922) p. 230 |
Gordon, 1922. The Mineralogy of Pennsylvania |
USA | |
| Gordon, Mineralogy of Pennsyvania, 1922 - p. 224 |
| Gordon: Min. Penn (1922) p. 230 |
Gordon, 1922. The Mineralogy of Pennsylvania |