Dictionaries give gesonnen and gesinnt similar translations: 'minded'. Is there a difference in meaning? Are they both past participles of the verb sinnen?
The verb "sinnen" seems nearly be unused in modern German language.
Different web sites about German grammar in the internet say that "gesinnt" is a participle of the word "sinnen" while other web sites say that it is an adjective coming from the word "Sinn" having nothing to do with the verb "sinnen".
There is a web site about the two words:
The words "gesonnen" and "gesinnt" are often are used as synonyms although this is not correct.
Most Germans use these words the wrong way.
There are two ways to say "gesinnt" for once you can say "sie sind gleich gesinnt" which mean, they share the same way of thinking. The other one is "er ist mir gut gesinnt", which means that "he" has a good opinion of me and is likely to act in my advantage. "Gesonnen" means basicly the same and can be used in the same way but not interchangeable, because it is a little more indirect, keeping a little more distance between the mentioned and talking persons.
Especially if talking within business and historical context "gesonnen" is much more common and appropriate.