Mineral is the opposite of Plant. Plant is related to Starter. 
Speculation is a type of Investment. House can be used for Investment. House can be used for Protection. Protection is related to Shell. 
Mineral <--Antonym--> Plant <--RelatedTo--> Starter 
Speculation --IsA--> Investment <--UsedFor-- House --UsedFor--> Protection <--RelatedTo--> Shell 