Here's why:

* Volcanic Origins: Martinique is a volcanic island, formed by the eruption of a volcanic hotspot. This means the island's base is primarily made up of lava and volcanic rock.

* Quartz Diorite Limestone: While not as common, there are also areas on Martinique with quartz diorite limestone formations. These are likely a result of volcanic activity interacting with marine sediments over time.

It's worth noting that other Caribbean islands like Guadeloupe and Dominica also have volcanic origins, with similar geological compositions.