I don't know why I should be doing due diligence for Mak...

I don't know why I should be doing due diligence for Mak investors but here is a single google reference to 16 inactive (or historical) phosphate mines in the state of Idaho alone. I found it after 30 seconds of research.
Unless you were smoking in the bathroom when your econ 1 teacher was explaining the law of supply and demand it doesn't take a genius to realize someone is probably looking at reopening some of these. My point is you don't have the same situation with potash. Maybe you could do some research and prove me wrong.

U.S. Geological Survey
Data Series 223
Spatial Database of Mining-Related Features in 2001 at Selected Phosphate Mines, Bannock, Bear Lake, Bingham, and Caribou Counties, Idaho
By Phillip R. Moyle and Helen Z. Kayser
2006

Map showing mining-related features in 2001 at selected phosphate mines, Bannock, Bear Lake, Bingham, and Caribou Counties, Idaho (from plate 1)

Introduction

This report describes the spatial database, PHOSMINE01, and the processes used to delineate mining-related features (active and inactive/historical) in the core of the southeastern Idaho phosphate resource area. The spatial data have varying degrees of accuracy and attribution detail. Classification of areas by type of mining-related activity at active mines is generally detailed; however, for many of the closed or inactive mines the spatial coverage does not differentiate mining-related surface disturbance features.

Nineteen phosphate mine sites are included in the study, three active phosphate mines – Enoch Valley (nearing closure), Rasmussen Ridge, and Smoky Canyon - and 16 inactive (or historical) phosphate mines – Ballard, Champ, Conda, Diamond Gulch, Dry Valley, Gay, Georgetown Canyon, Henry, Home Canyon, Lanes Creek, Maybe Canyon, Mountain Fuel, Trail Canyon, Rattlesnake, Waterloo, and Wooley Valley. Approximately 6,000 hc (15,000 ac), or 60 km2 (23 mi2) of phosphate mining-related surface disturbance are documented in the spatial coverage. Spatial data for the inactive mines is current because no major changes have occurred; however, the spatial data for active mines were derived from digital maps prepared in early 2001 and therefore recent activity is not included. The inactive Gay Mine has the largest total area of disturbance, 1,900 hc (4,700 ac) or about 19 km2 (7.4 mi2). It encompasses over three times the disturbance area of the next largest mine, the Conda Mine with 610 hc (1,500 ac), and it is nearly four times the area of the Smoky Canyon Mine, the largest of the active mines with about 550 hc (1,400 ac).

The wide range of phosphate mining-related surface disturbance features (141) from various industry maps were reduced to 15 types or features based on a generic classification system used for this study: mine pit; backfilled mine pit; waste rock dump; adit and waste rock dump; ore stockpile; topsoil stockpile; tailings or tailings pond; sediment catchment; facilities; road; railroad; water reservoir; disturbed land, undifferentiated; and undisturbed land. In summary, the spatial coverage includes polygons totaling about 1,100 hc (2,800 ac) of mine pits, 440 hc (1100 ac) of backfilled mine pits, 1,600 hc (3,800 ac) of waste rock dumps, 31 hc (75 ac) of ore stockpiles, and 44 hc (110 ac) of tailings or tailings ponds. Areas of undifferentiated phosphate mining-related land disturbances, called “disturbed land, undifferentiated,” total about 2,200 hc (5,500 ac) or nearly 22 km2 (8.6 mi2). No determination has been made as to status of reclamation on any of the lands. Subsequent site-specific studies to delineate distinct mine features will allow additional revisions to this spatial database.

PDF Files
Download the text for this report as a 58-page PDF file (ds-223_text.pdf; 4.8 MB).

Download the plate for this report as a ~28" x 38" PDF file (ds-223_plate.pdf; 4 MB).

Data
Readme file (ds-223_readme.txt; 12 KB).

ds-223_metadata folder: contains eight metadata files in html format that provide information about the spatial databases in this report (396 KB).

ds-223_metadata.zip: compressed file of the ds-223_metadata directory linked above; contains all eight .htm files in a single package (72 KB).