Babylon.js/Babylon/Particles/babylon.particle.d.ts

declare module BABYLON {
    class Particle {
        public position: Vector3;
        public direction: Vector3;
        public color: Color4;
        public colorStep: Color4;
        public lifeTime: number;
        public age: number;
        public size: number;
        public angle: number;
        public angularSpeed: number;
    }
}