I fish a bottom bumping lure on a 6 1/2 and a 7 foot rod. I use braided line. When I let the lure drop, I can feel the lure hit the bottom. My question is how do I tell what it is made of?

Your depth sounder (sonar) is more appropriate for assessing the bottom composition:

Wide Band: Rock Sand Clay

Moderate Band: Mud Silt Branches Fish

Narrow Band: Weeds Surface Clutter Thermocline

Bedrock (ledgerock) usually gives you a double-bounce reading

or even a triple or quadruplet-bounce in shallow water.

Roger

Thanx for your response. I usually fish from shore on week nights. So the sonar doesnt really come into play. But I have read articles and heard people say that it can be done.

Needless to say, a lure bounced on a hard bottom will produce a sharp, crisp response,

whereas a lure thumped on a soft bottom will return a dull, cushy response.  

Brush will have a springy feel (and usually hang you up).

Roger

I currently have the misfortune of fishing without a depthfinder most of the time so I like to drop a trebble hook where I think there might be weeds & it will let you know based on what it brings up with it

A sensative rod, fished with braided line and a heavy weighted lure like a jig will give you an excellent sense of what the bottom is like.

Rolo is on target with the feel of the bottom composition.

It can take a little practice to learn the subtleties but it is actually kind of fun.  If you drag the jig, or weedless t-rigged worm you can also find little humps, hole, isolated patches of cover etc.

On my home lake, like many lakes and canals in Florida, there is virtually no structure, so finding subtle changes in the bottom countour can yield excellent results.

The heavier the weight the easier it is to do this.