The not readable SD card or unreadable SD card pictures on your Mac are symptoms when the SD card gets corrupted. Stop using the corrupted SD card immediately when such a situation occurs. There is a great chance to recover pictures from the corrupted SD card with professional data recovery software.
SD card corruption error may be triggered when the SD card has been used on multiple types of devices or has been physically removed from a device while a file was being accessed or transferred. A corrupted SD card is accompanied by some symptoms such as the SD card is not detected, read/write issues, connection issues, the pictures disappearing from the SD card, wrong SD card capacity, and so on.
If unluckily, your SD card gets corrupted, you should recover data from it ASAP and then fix it to make it usable again. Pick up the best recovery software for SD card to rescue your lost pictures. Here, I'd like to recommend you the iBoysoft Data Recovery for Mac, it is professional, 100% secure, reliable, and easy to use.
Steps to recover lost pictures from a corrupted SD card on Mac:
Step 1. Download and install iBoysoft Data Recovery for Mac.
Step 2. Connect the SD card and launch the recovery software.
Step 3. Select the SD card under Data Recovery from the left sidebar.
Step 4. Click the Search for Lost Data at the right bottom to start scanning.
Step 5. Filter files by different categories and then preview recoverable files.
Step 6. Select the desired pictures and click the Recover button to save them to a different location.
Now, you have recovered the lost pictures from the corrupted SD card, you can continue to repair corrupted SD card without losing data so that you can read and write data to it as usual.