If you load the following data into Cassandra and try to read from it with the ruby-driver, you will get errors thrown when reading the "invalid" lines (cannot convert nil into string).

CREATE TABLE broken (
	my_id text PRIMARY KEY,
	bad decimal
);

INSERT INTO broken (my_id, bad) VALUES ('invalid', 1.0149E+7);
INSERT INTO broken (my_id, bad) VALUES ('valid', 101490000000.0000);

INSERT INTO broken (my_id, bad) VALUES ('invalid2', 1.0E+7);
INSERT INTO broken (my_id, bad) VALUES ('valid2', 10000000.0);